Mintu Turakhia M.D. M.A.S. is a cardiac electrophysiologist, outcomes researcher, and clinical trialist. Dr. Turakhia has an active, highly-funded multidisciplinary program in atrial fibrillation, where uses large datasets to examine quality, outcomes, and risk prediction for heart rhythm disorders. As the Executive Director of Stanford’s new Center for Digital Health, he is the principal investigator of several multi-center trials to test digital health tools and wearable devices to screen and manage heart rhythm disorders. In his clinical role as Director of Cardiac Electrophysiology at the VA, Dr. Turakhia performs invasive procedures such as catheter ablation and device implantation to treat heart rhythm disorders. Dr. Turakhia is a Fellow of the American Heart Association, American College of Cardiology, and Heart Rhythm Society.
- Arrhythmias, Cardiac
- Cardiology (Heart)
- Death, Sudden, Cardiac
- Catheter Ablation
- Atrial Fibrillation
- Implantable Defibrillators
- Tachycardia, Supraventricular
- Clinical Cardiac Electrophysiology
Co-Chairperson, VA Health Services & Research Career Development Conference (2009 - 2010)
Chair, Writing Group, American Heart Association Telemetry Latency Advisory (2010 - Present)
Member, Young Clinicians and Investigators Committee, American Heart Association Council of Quality and Outcomes Research (2010 - Present)
Member, Electrocardiography and Arrhythmias Committee, American Heart Association (2009 - Present)
Cardiac Electrophysiologist, Stanford Hospital and Clinics (2008 - Present)
Director, Cardiac Electrophysiology, Palo Alto VA Health Care System (2008 - Present)
Honors & Awards
E. William Hancock Faculty Teaching Award, Stanford Division of Cardiovascular Medicine (6/2010)
Department of Medicine Teaching Award, Stanford Department of Medicine (12/2010)
Board Certification: Clinical Cardiac Electrophysiology, American Board of Internal Medicine (2009)
Professional Education:UCSF - MAS (2008) CA
Fellowship:Univ of California San Francisco (2008) CA
Board Certification: Cardiovascular Disease, American Board of Internal Medicine (2006)
Fellowship:Univ of California San Francisco (2006) CA
Residency:Brigham and Women's Hospital Harvard Medical School (2003) MA
Internship:Brigham and Women's Hospital Harvard Medical School (2001) MA
Medical Education:Univ of California San Francisco (2000) CA
Community and International Work
Research Chair, Mountain View, CA
Cardiovascular risk in South Asians
South Asian Heart Center, El Camino Hospital
Opportunities for Student Involvement
Current Research and Scholarly Interests
Dr. Turakhia has an active clinical research program, with funding from AHA, VA, NIH, the medical device industry, and foundations. His research program aims to improve the treatment of heart rhythm disorders, with an emphasis on atrial fibrillation, by evaluating quality and variation of care, comparative and cost-effectiveness of therapies, and risk prediction. Dr. Turakhia has extensive expertise in using large administrative and claims databases for this work. His TREAT-AF retrospective study of over 500,000 patients with newly-diagnosed AF is the largest known research cohort of AF patients. He has served as study PI or chairman of several prominent single- and multicenter trials in atrial fibrillation, investigational devices for electrophysiology procedures, digital health interventions, and sensor technologies.
His other research interests include technology assessment of new device-based therapies and the impact of changing health policy and reform on the delivery of arrhythmia care. Dr. Turakhia is a Fellow of the American Heart Association, American College of Cardiology, and Heart Rhythm Society.
- Atrial Fibrillation Burden and Short-Term Risk of Stroke Case-Crossover Analysis of Continuously Recorded Heart Rhythm From Cardiac Electronic Implanted Devices CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY 2015; 8 (5): 1040-1047
Site-level variation in and practices associated with dabigatran adherence.
2015; 313 (14): 1443-1450
Unlike warfarin, which requires routine laboratory testing and dose adjustment, target-specific oral anticoagulants like dabigatran do not. However, optimal follow-up infrastructure and modifiable site-level factors associated with improved adherence to dabigatran are unknown.To assess site-level variation in dabigatran adherence and to identify site-level practices associated with higher dabigatran adherence.Mixed-methods study involving retrospective quantitative and cross-sectional qualitative data. A total of 67 Veterans Health Administration sites with 20 or more patients filling dabigatran prescriptions between 2010 and 2012 for nonvalvular atrial fibrillation were sampled (4863 total patients; median, 51 patients per site). Forty-seven pharmacists from 41 eligible sites participated in the qualitative inquiry.Site-level practices identified included appropriate patient selection, pharmacist-driven patient education, and pharmacist-led adverse event and adherence monitoring.Dabigatran adherence (intensity of drug use during therapy) defined by proportion of days covered (ratio of days supplied by prescription to follow-up duration) of 80% or more.The median proportion of patients adherent to dabigatran was 74% (interquartile range [IQR], 66%-80%). After multivariable adjustment, dabigatran adherence across sites varied by a median odds ratio of 1.57. Review of practices across participating sites showed that appropriate patient selection was performed at 31 sites, pharmacist-led education was provided at 30 sites, and pharmacist-led monitoring at 28 sites. The proportion of adherent patients was higher at sites performing appropriate selection (75% vs 69%), education (76% vs 66%), and monitoring (77% vs 65%). Following multivariable adjustment, association between pharmacist-led education and dabigatran adherence was not statistically significant (relative risk [RR], 0.94; 95% CI, 0.83-1.06). Appropriate patient selection (RR, 1.14; 95% CI, 1.05-1.25), and provision of pharmacist-led monitoring (RR, 1.25; 95% CI, 1.11-1.41) were associated with better patient adherence. Additionally, longer duration of monitoring and providing more intensive care to nonadherent patients in collaboration with the clinician improved adherence.Among nonvalvular atrial fibrillation patients treated with dabigatran, there was variability in patient medication adherence across Veterans Health Administration sites. Specific pharmacist-based activities were associated with greater patient adherence to dabigatran.
View details for DOI 10.1001/jama.2015.2761
View details for PubMedID 25871670
- Association Between Success Rate and Citation Count of Studies of Radiofrequency Catheter Ablation for Atrial Fibrillation Possible Evidence of Citation Bias CIRCULATION-CARDIOVASCULAR QUALITY AND OUTCOMES 2014; 7 (5): 687-692
Increased Mortality Associated With Digoxin in Contemporary Patients With Atrial Fibrillation: Findings From the TREAT-AF Study.
Journal of the American College of Cardiology
2014; 64 (7): 660-668
Despite endorsement of digoxin in clinical practice guidelines, there exist limited data on its safety in atrial fibrillation/flutter (AF).The goal of this study was to evaluate the association of digoxin with mortality in AF.Using complete data of the TREAT-AF (The Retrospective Evaluation and Assessment of Therapies in AF) study from the U.S. Department of Veterans Affairs (VA) healthcare system, we identified patients with newly diagnosed, nonvalvular AF seen within 90 days in an outpatient setting between VA fiscal years 2004 and 2008. We used multivariate and propensity-matched Cox proportional hazards to evaluate the association of digoxin use with death. Residual confounding was assessed by sensitivity analysis.Of 122,465 patients with 353,168 person-years of follow-up (age 72.1 ± 10.3 years, 98.4% male), 28,679 (23.4%) patients received digoxin. Cumulative mortality rates were higher for digoxin-treated patients than for untreated patients (95 vs. 67 per 1,000 person-years; p < 0.001). Digoxin use was independently associated with mortality after multivariate adjustment (hazard ratio [HR]: 1.26, 95% confidence interval [CI]: 1.23 to 1.29, p < 0.001) and propensity matching (HR: 1.21, 95% CI: 1.17 to 1.25, p < 0.001), even after adjustment for drug adherence. The risk of death was not modified by age, sex, heart failure, kidney function, or concomitant use of beta-blockers, amiodarone, or warfarin.Digoxin was associated with increased risk of death in patients with newly diagnosed AF, independent of drug adherence, kidney function, cardiovascular comorbidities, and concomitant therapies. These findings challenge current cardiovascular society recommendations on use of digoxin in AF.
View details for DOI 10.1016/j.jacc.2014.03.060
View details for PubMedID 25125296
View details for PubMedCentralID PMC4405246
- Warfarin treatment in patients with atrial fibrillation and advanced chronic kidney disease: sins of omission or commission? JAMA 2014; 311 (9): 913-915
Burden, timing, and relationship of cardiovascular hospitalization to mortality among Medicare beneficiaries with newly diagnosed atrial fibrillation.
American heart journal
2013; 166 (3): 573-580
Limited data exist on the burden and relationship of cardiovascular (CV) hospitalization to mortality after newly diagnosed with atrial fibrillation (AF).Using a 20% sample of nationwide Medicare Part A and B claims data, we performed a retrospective cohort study of Medicare beneficiaries with newly diagnosed AF (2004-2008). Cox proportional hazards time-varying exposures were used to determine the risk of death among patients with CV hospitalization after AF diagnosis.Of 228,295 patients (mean age 79.6 ± 7.4 years, 56% female), 57% had a CV hospitalization after diagnosis of AF (41% in the first year). The most common primary CV hospitalization diagnoses were AF/supraventricular arrhythmias (21%), heart failure (19%), myocardial infarction (11%), and stroke/transient ischemic attack (7.7%). Incidence rates per 1,000 person-years among patients with and without CV hospitalization were 114 and 87, respectively, for all-cause mortality. After adjustment for covariates and time to CV hospitalization, the hazard of mortality among newly diagnosed AF patients with CV hospitalization, compared with those without CV hospitalization, was higher (hazard ratio 1.22, 95% CI 1.20-1.24).Cardiovascular hospitalization is common in the first year after AF diagnosis. Atrial fibrillation, heart failure, myocardial infarction, and stroke/transient ischemic attack account for half of primary hospitalization diagnosis. Cardiovascular hospitalization is independently associated with mortality, irrespective of time from diagnosis to first hospitalization, and represents a critical inflection point in survival trajectory. These findings highlight the importance of CV hospitalization as a marker of disease progression and poor outcomes. Efforts to clarify the determinants of hospitalization could inform interventions to reduce admissions and improve survival.
View details for DOI 10.1016/j.ahj.2013.07.003
View details for PubMedID 24016509
US Health Care Policy and Reform: implications for cardiac electrophysiology
JOURNAL OF INTERVENTIONAL CARDIAC ELECTROPHYSIOLOGY
2013; 36 (2): 129-136
In response to unsustainably rising costs, variable quality and access to health care, and the projected insolvency of vital safety net insurance programs, the federal government has proposed important health policy and regulatory changes in the USA. The US Supreme Court's decision to uphold most of the major provisions of the Affordable Care Act will lead to some of the most sweeping government reforms on entitlements since the creation of Medicare. Furthermore, implementation of new organizational, reimbursement, and health care delivery models will strongly affect the practice of cardiac electrophysiology. In this brief review, we will provide background and context to the problem of rising health care costs and describe salient reforms and their projected impacts on the field and practice of cardiac electrophysiology.
View details for DOI 10.1007/s10840-012-9773-3
View details for Web of Science ID 000316749200005
View details for PubMedID 23397248
Differences and trends in stroke prevention anticoagulation in primary care vs cardiology specialty management of new atrial fibrillation: The Retrospective Evaluation and Assessment of Therapies in AF (TREAT-AF) study.
American heart journal
2013; 165 (1): 93-101 e1
Atrial fibrillation and flutter (AF, collectively) cause stroke. We evaluated whether treating specialty influences warfarin prescription in patients with newly diagnosed AF.In the TREAT-AF study, we used Veterans Health Administration health record and claims data to identify patients with newly diagnosed AF between October 2004 and November 2008 and at least 1 internal medicine/primary care or cardiology outpatient encounter within 90 days after diagnosis. The primary outcome was prescription of warfarin.In 141,642 patients meeting the inclusion criteria, the mean age was 72.3 ± 10.2 years, 1.48% were women, and 25.8% had cardiology outpatient care. Cardiology-treated patients had more comorbidities and higher mean CHADS2 scores (1.8 vs 1.6, P < .0001). Warfarin use was higher in cardiology-treated vs primary care only-treated patients (68.6% vs 48.9%, P < .0001). After covariate and site-level adjustment, cardiology care was significantly associated with warfarin use (odds ratio [OR] 2.05, 95% CI 1.99-2.11). These findings were consistent across a series of adjusted models (OR 2.05-2.20), propensity matching (OR 1.98), and subgroup analyses (OR 1.58-2.11). Warfarin use in primary-care-only patients declined from 2004 to 2008 (51.6%-44.0%, P < .0001), whereas the adjusted odds of warfarin receipt with cardiology care (vs primary care) increased from 2004 to 2008 (1.88-2.24, P < .0001).In patients with newly diagnosed AF, we found large differences in anticoagulation use by treating specialty. A divergent 5-year trend of risk-adjusted warfarin use was observed. Treating specialty influences stroke prevention care and may impact clinical outcomes.
View details for DOI 10.1016/j.ahj.2012.10.010
View details for PubMedID 23237139
- Differences and trends in stroke prevention anticoagulation in primary care vs cardiology specialty management of new atrial fibrillation: The Retrospective Evaluation and Assessment of Therapies in AF (TREAT-AF) study AMERICAN HEART JOURNAL 2013; 165 (1): 93-?
Cost-Effectiveness of Dabigatran Compared With Warfarin for Stroke Prevention in Atrial Fibrillation
ANNALS OF INTERNAL MEDICINE
2011; 154 (1): 1-U129
Warfarin reduces the risk for ischemic stroke in patients with atrial fibrillation (AF) but increases the risk for hemorrhage. Dabigatran is a fixed-dose, oral direct thrombin inhibitor with similar or reduced rates of ischemic stroke and intracranial hemorrhage in patients with AF compared with those of warfarin.To estimate the quality-adjusted survival, costs, and cost-effectiveness of dabigatran compared with adjusted-dose warfarin for preventing ischemic stroke in patients 65 years or older with nonvalvular AF.Markov decision model.The RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) trial and other published studies of anticoagulation. The cost of dabigatran was estimated on the basis of pricing in the United Kingdom.Patients aged 65 years or older with nonvalvular AF and risk factors for stroke (CHADS₂ score ≥1 or equivalent) and no contraindications to anticoagulation.Lifetime.Societal.Warfarin anticoagulation (target international normalized ratio, 2.0 to 3.0); dabigatran, 110 mg twice daily (low dose); and dabigatran, 150 mg twice daily (high dose).Quality-adjusted life-years (QALYs), costs (in 2008 U.S. dollars), and incremental cost-effectiveness ratios.The quality-adjusted life expectancy was 10.28 QALYs with warfarin, 10.70 QALYs with low-dose dabigatran, and 10.84 QALYs with high-dose dabigatran. Total costs were $143 193 for warfarin, $164 576 for low-dose dabigatran, and $168 398 for high-dose dabigatran. The incremental cost-effectiveness ratios compared with warfarin were $51 229 per QALY for low-dose dabigatran and $45 372 per QALY for high-dose dabigatran.The model was sensitive to the cost of dabigatran but was relatively insensitive to other model inputs. The incremental cost-effectiveness ratio increased to $50 000 per QALY at a cost of $13.70 per day for high-dose dabigatran but remained less than $85 000 per QALY over the full range of model inputs evaluated. The cost-effectiveness of high-dose dabigatran improved with increasing risk for stroke and intracranial hemorrhage.Event rates were largely derived from a single randomized clinical trial and extrapolated to a 35-year time frame from clinical trials with approximately 2-year follow-up.In patients aged 65 years or older with nonvalvular AF at increased risk for stroke (CHADS₂ score ≥1 or equivalent), dabigatran may be a cost-effective alternative to warfarin depending on pricing in the United States.American Heart Association and Veterans Affairs Health Services Research & Development Service.
View details for Web of Science ID 000285830900001
View details for PubMedID 21041570
Transforming the care of atrial fibrillation with mobile health
JOURNAL OF INTERVENTIONAL CARDIAC ELECTROPHYSIOLOGY
2016; 47 (1): 45-50
Atrial fibrillation (AF) is a multifaceted and highly variable disease that is often difficult to manage within the traditional health-care model. The conventional model of regular or pre-scheduled appointments with physicians or allied health professionals is poorly suited to the unpredictable and often urgent clinical needs of patients with AF. Mobile health (mHealth) has the potential to dramatically transform the delivery and quality of AF care. In this brief review, we summarize the current limitations and evidence gaps in treating patients with AF. We then describe the current mHealth landscape, changes in telehealth coverage and reimbursement, and recent technological advances of smartphones, mobile applications, and connected wearable devices. We also describe important barriers and challenges, such as clinical management of large volumes of data, application of predictive analytics/machine learning, and the need for high-quality randomized clinical trials.
View details for DOI 10.1007/s10840-016-0136-3
View details for Web of Science ID 000387110400007
View details for PubMedID 27306552
Cost-Effectiveness of Implantable Pulmonary Artery Pressure Monitoring in Chronic Heart Failure
2016; 4 (5): 368-375
This study aimed to evaluate the cost-effectiveness of the CardioMEMS (CardioMEMS Heart Failure System, St Jude Medical Inc, Atlanta, Georgia) device in patients with chronic heart failure.The CardioMEMS device, an implantable pulmonary artery pressure monitor, was shown to reduce hospitalizations for heart failure and improve quality of life in the CHAMPION (CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients) trial.We developed a Markov model to determine the hospitalization, survival, quality of life, cost, and incremental cost-effectiveness ratio of CardioMEMS implantation compared with usual care among a CHAMPION trial cohort of patients with heart failure. We obtained event rates and utilities from published trial data; we used costs from literature estimates and Medicare reimbursement data. We performed subgroup analyses of preserved and reduced ejection fraction and an exploratory analysis in a lower-risk cohort on the basis of the CHARM (Candesartan in Heart failure: Reduction in Mortality and Morbidity) trials.CardioMEMS reduced lifetime hospitalizations (2.18 vs. 3.12), increased quality-adjusted life-years (QALYs) (2.74 vs. 2.46), and increased costs ($176,648 vs. $156,569), thus yielding a cost of $71,462 per QALY gained and $48,054 per life-year gained. The cost per QALY gained was $82,301 in patients with reduced ejection fraction and $47,768 in those with preserved ejection fraction. In the lower-risk CHARM cohort, the device would need to reduce hospitalizations for heart failure by 41% to cost <$100,000 per QALY gained. The cost-effectiveness was most sensitive to the device's durability.In populations similar to that of the CHAMPION trial, the CardioMEMS device is cost-effective if the trial effectiveness is sustained over long periods. Post-marketing surveillance data on durability will further clarify its value.
View details for DOI 10.1016/j.jchf.2015.12.015
View details for Web of Science ID 000375347200006
View details for PubMedID 26874380
- The precise timing of tachycardia entrainment is determined by the postpacing interval, the tachycardia cycle length, and the pacing rate: Theoretical insights and practical applications HEART RHYTHM 2016; 13 (3): 695-703
- Sleep disordered breathing and cardiovascular risk in older patients initiating dialysis in the United States: a retrospective observational study using medicare data BMC NEPHROLOGY 2016; 17
Racial Differences in Quality of Anticoagulation Therapy for Atrial Fibrillation (from the TREAT-AF Study)
AMERICAN JOURNAL OF CARDIOLOGY
2016; 117 (1): 61-68
The influence of race on quality of anticoagulation control is not well described. We examined the association between race, international normalized ratio (INR) monitoring intensity, and INR control in warfarin-treated patients with atrial fibrillation (AF). Using data from the Veterans Health Administration (VHA), we performed a retrospective cohort study of 184,161 patients with a new diagnosis of AF/flutter from 2004 to 2012 who received any VHA prescription within 90 days of diagnosis. The primary predictor was race, ascertained from multiple VHA and linked Medicare demographic files. The primary outcome was first-year and long-term time in therapeutic range (TTR) of INR 2.0 to 3.0. Secondary outcomes were INR monitoring intensity and warfarin persistence. Of the 116,021 patients who received warfarin in the cohort, INR monitoring intensity was similar across racial groups. However, TTR was lowest in blacks and highest in whites (first year 0.49 ± 0.23 vs 0.57 ± 0.21, p <0.001; long term 0.52 ± 0.20 vs 0.59 ± 0.18, p <0.001); 64% of whites and 49% of blacks had long-term TTR >55% (p <0.001). After adjusting for site and patient-level covariates, black race was associated with lower first-year and long-term TTRs (4.2% and 4.1% below the conditional mean, relative to whites; p <0.0001 for both). One-year warfarin persistence was slightly lower in blacks compared to whites (58% vs 60%, p <0.0001). In conclusion, in patients with AF anticoagulated with warfarin, differences in INR control are most evident among blacks, underscoring the need to determine if other types of intensive management or warfarin alternatives may be necessary to improve anticoagulation among vulnerable AF populations.
View details for DOI 10.1016/j.amjcard.2015.09.047
View details for Web of Science ID 000368048900010
Amiodarone and risk of death in contemporary patients with atrial fibrillation: Findings from The Retrospective Evaluation and Assessment of Therapies in AF study.
American heart journal
2015; 170 (5): 1033-1041 e1
There are limited data on mortality outcomes associated with use of amiodarone in atrial fibrillation and flutter (AF).We evaluated the association of amiodarone use with mortality in patients with newly diagnosed AF using complete data from the Department of Veterans Affairs national health care system. We included patients seen in an outpatient setting within 90 days of a new diagnosis for nonvalvular AF between Veterans Affairs fiscal years 2004 and 2008. Multivariate analysis and propensity-matched Cox proportional hazards regression were used to evaluate the association of amiodarone use to death.Of 122,465 patients (353,168 person-years of follow-up, age 72.1 ± 10.3 years, 98.4% males), amiodarone was prescribed in 11,655 (9.5%). Cumulative, unadjusted mortality rates were higher for amiodarone recipients than for nonrecipients (87 vs 73 per 1,000 person-years, P < .001). However, in multivariate and propensity-matched survival analyses, there was no significant difference in mortality (multivariate hazard ratio 1.01, 95% CI 0.97-1.05, P = .51, and propensity-matched hazard ratio 1.02, 95% CI 0.97-1.07, P = .45). The hazard of death was not modified by age, sex, heart failure, kidney function, β-blocker use, or warfarin use, but there was evidence of effect modification among patients diagnosed with AF as an inpatient versus outpatient.In a national health care system population of newly diagnosed AF, overall use of amiodarone as an early treatment strategy was not associated with mortality.
View details for DOI 10.1016/j.ahj.2015.07.023
View details for PubMedID 26542514
View details for PubMedCentralID PMC4800972
- Amiodarone and risk of death in contemporary patients with atrial fibrillation: Findings from The Retrospective Evaluation and Assessment of Therapies in AF study AMERICAN HEART JOURNAL 2015; 170 (5): 1033-U231
Outcomes After Warfarin Initiation in a Cohort of Hemodialysis Patients With Newly Diagnosed Atrial Fibrillation.
American journal of kidney diseases
2015; 66 (4): 677-688
Although warfarin is indicated to prevent ischemic strokes in most patients with atrial fibrillation (AF), evidence supporting its use in hemodialysis patients is limited. Our aim was to examine outcomes after warfarin therapy initiation, relative to no warfarin use, following incident AF in a large cohort of hemodialysis patients who had comprehensive prescription drug coverage through Medicare Part D.Retrospective observational cohort study.Patients in the US Renal Data System undergoing maintenance hemodialysis who had AF newly diagnosed in 2007 to 2011, with Medicare Part D coverage, who had no recorded history of warfarin use.Warfarin therapy initiation, identified by a filled prescription within 30 days of the AF event.Death, ischemic stroke, hemorrhagic stroke, severe gastrointestinal bleeding, and composite outcomes.HRs estimated by applying Cox regression to an inverse probability of treatment and censoring-weighted cohort.Of 12,284 patients with newly diagnosed AF, 1,838 (15%) initiated warfarin therapy within 30 days; however, ∼70% discontinued its use within 1 year. In intention-to-treat analyses, warfarin use was marginally associated with a reduced risk of ischemic stroke (HR, 0.68; 95% CI, 0.47-0.99), but not with the other outcomes. In as-treated analyses, warfarin use was associated with reduced mortality (HR, 0.84; 95% CI, 0.73-0.97).Short observation period, limited number of nonfatal events, limited generalizability of results to more affluent patients.In hemodialysis patients with incident AF, warfarin use was marginally associated with reduced risk of ischemic stroke, and there was a signal toward reduced mortality in as-treated analyses. These results support clinical equipoise regarding the use of warfarin in hemodialysis patients and underscore the need for randomized trials to fill this evidence gap.
View details for DOI 10.1053/j.ajkd.2015.05.019
View details for PubMedID 26162653
- Defibrillator implantations for primary prevention in the United States: Inappropriate care or inadequate documentation: Insights from the National Cardiovascular Data ICD Registry. Heart rhythm 2015; 12 (10): 2086-2093
- Economic Burden of Undiagnosed Nonvalvular Atrial Fibrillation in the United States AMERICAN JOURNAL OF CARDIOLOGY 2015; 116 (5): 733-739
- A validated risk model for 1-year mortality after primary prevention implantable cardioverter defibrillator placement AMERICAN HEART JOURNAL 2015; 170 (2): 281-U119
Early detection of occult atrial fibrillation and stroke prevention
2015; 101 (14): 1097-1102
Atrial fibrillation (AF) is a very common arrhythmia and significantly increases stroke risk. This risk can be mitigated with oral anticoagulation, but AF is often asymptomatic, or occult, preventing timely detection and treatment. Accordingly, occult AF may cause stroke before it is clinically diagnosed. Currently, guidelines for the early detection and treatment of occult AF are limited. This review addresses recent advancements in occult AF detection methods, identification of populations at high risk for occult AF, the treatment of occult AF with oral anticoagulation, as well as ongoing trials that may answer critically important questions regarding occult AF screening.
View details for DOI 10.1136/heartjnl-2015-307588
View details for Web of Science ID 000357038700007
View details for PubMedID 25935765
- Individual and Combined Risk Factors for Incident Atrial Fibrillation and Incident Stroke: An Analysis of 3 Million At-Risk US Patients JOURNAL OF THE AMERICAN HEART ASSOCIATION 2015; 4 (7)
Does Age Influence Cardiac Resynchronization Therapy Use and Outcome?
JACC. Heart failure
2015; 3 (6): 497-504
This study sought to describe the use of CRT-D and its association with survival for older patients.Many patients who receive cardiac resynchronization therapy with defibrillator (CRT-D) in practice are older than those included in clinical trials.We identified patients undergoing ICD implantation in the National Cardiovascular Disease Registry (NCDR) ICD registry from 2006 to 2009, who also met clinical trial criteria for CRT, including left ventricular ejection fraction (LVEF) ≤35%, QRS ≥120 ms, and New York Heart Association (NYHA) functional class III or IV. NCDR registry data were linked to the social security death index to determine the primary outcome of time to death from any cause. We identified 70,854 patients from 1,187 facilities who met prior trial criteria for CRT-D. The mean age of the 58,147 patients receiving CRT-D was 69.4 years with 6.4% of patients age 85 or older. CRT use was 80% or higher among candidates in all age groups. Follow-up was available for 42,285 patients age ≥65 years at 12 months.Receipt of CRT-D was associated with better survival at 1 year (82.1% vs. 77.1%, respectively) and 4 years (54.0% vs. 46.2% , respectively) than in those receiving only an ICD (p < 0.001). The CRT association with improved survival was not different for different age groups (p = 0.86 for interaction).More than 80% of older patients undergoing ICD implantation who were candidates for a CRT-D received the combined device. Mortality in older patients undergoing ICD implantation was high but was lower for those receiving CRT-D.
View details for DOI 10.1016/j.jchf.2015.01.012
View details for PubMedID 25982109
Feasibility of Extended Ambulatory Electrocardiogram Monitoring to Identify Silent Atrial Fibrillation in High-risk Patients: The Screening Study for Undiagnosed Atrial Fibrillation (STUDY-AF)
2015; 38 (5): 285-292
Identification of silent atrial fibrillation (AF) could prevent stroke and other sequelae.Screening for AF using continuous ambulatory electrocardiographic (ECG) monitoring can detect silent AF in asymptomatic in patients with known risk factors.We performed a single-center prospective screening study using a wearable patch-based device that provides up to 2 weeks of continuous ambulatory ECG monitoring (iRhythm Technologies, Inc.). Inclusion criteria were age ≥55 years and ≥2 of the following risk factors: coronary disease, heart failure, hypertension, diabetes, sleep apnea. We excluded patients with prior AF, stroke, transient ischemic attack, implantable pacemaker or defibrillator, or with palpitations or syncope in the prior year.Out of 75 subjects (all male, age 69 ± 8.0 years; ejection fraction 57% ± 8.7%), AF was detected in 4 subjects (5.3%; AF burden 28% ± 48%). Atrial tachycardia (AT) was present in 67% (≥4 beats), 44% (≥8 beats), and 6.7% (≥60 seconds) of subjects. The combined diagnostic yield of sustained AT/AF was 11%. In subjects without sustained AT/AF, 11 (16%) had ≥30 supraventricular ectopic complexes per hour.Outpatient extended ECG screening for asymptomatic AF is feasible, with AF identified in 1 in 20 subjects and sustained AT/AF identified in 1 in 9 subjects, respectively. We also found a high prevalence of asymptomatic AT and frequent supraventricular ectopic complexes, which may be relevant to development of AF or stroke. If confirmed in a larger study, primary screening for AF could have a significant impact on public health.
View details for DOI 10.1002/clc.22387
View details for Web of Science ID 000354748000005
View details for PubMedID 25873476
View details for PubMedCentralID PMC4654330
Cardiovascular Disease Performance Measures in the Outpatient Setting in India: Insights From the American College of Cardiology's PINNACLE India Quality Improvement Program (PIQIP)
JOURNAL OF THE AMERICAN HEART ASSOCIATION
2015; 4 (5)
India has a growing burden of cardiovascular disease (CVD), yet data on the quality of outpatient care for patients with coronary artery disease, heart failure, and atrial fibrillation in India are very limited. We collected data on performance measures for 68 196 unique patients from 10 Indian cardiology outpatient departments from January 1, 2011, to February 5, 2014, in the American College of Cardiology's PINNACLE (Practice Innovation and Clinical Excellence) India Quality Improvement Program (PIQIP). PIQIP is India's first national outpatient CVD quality-improvement program.In the PIQIP registry, we estimated the prevalence of CVD risk factors (hypertension, diabetes, dyslipidemia, and current tobacco use) and CVD among outpatients. We examined adherence with performance measures established by the American College of Cardiology, the American Heart Association, and the American Medical Association Physician Consortium for Performance Improvement for coronary artery disease, heart failure, and atrial fibrillation. There were a total of 68 196 patients (155 953 patient encounters), with a mean age of 50.6 years (SD 18.2 years). Hypertension was present in 29.7% of patients, followed by diabetes (14.9%), current tobacco use (7.6%), and dyslipidemia (6.5%). Coronary artery disease was present in 14.8%, heart failure was noted in 4.0%, and atrial fibrillation was present in 0.5% of patients. Among eligible patients, the reported use of medications was as follows: aspirin in 48.6%, clopidogrel in 37.1%, and statin-based lipid-lowering therapy in 50.6% of patients with coronary artery disease; RAAS (renin-angiotensin-aldosterone system) antagonist in 61.9% and beta-blockers in 58.1% of patients with heart failure; and oral anticoagulants in 37.0% of patients with atrial fibrillation.This pilot study, initiated to improve outpatient CVD care in India, presents our preliminary results and barriers to data collection and demonstrates that such an initiative is feasible in a resource-limited environment. In addition, we attempted to outline areas for further improvement in outpatient CVD care delivery in India.
View details for DOI 10.1161/JAHA.115.001910
View details for Web of Science ID 000356347600018
View details for PubMedID 25994444
Safety of ventricular tachycardia ablation in clinical practice: findings from 9699 hospital discharge records.
Circulation. Arrhythmia and electrophysiology
2015; 8 (2): 362-370
Outcomes of ventricular tachycardia (VT) ablation have been described in clinical trials and single-center studies. We assessed the safety of VT ablation in clinical practice.Using administrative hospitalization data between 1994 and 2011, we identified hospitalizations with primary diagnosis of VT (International Classification of Diseases-9 Clinical Modification code: 427.1) and cardiac ablation (International Classification of Diseases-9 Clinical Modification code: 37.34). We quantified in-hospital adverse events (AEs), including death, stroke, intracerebral hemorrhage, pericardial complications, hematoma or hemorrhage, blood transfusion, or cardiogenic shock. Secondary outcomes included major AEs (stroke, tamponade, or death) and death. Multivariable mixed effects models identified patient and hospital characteristics associated with AEs. Of 9699 hospitalizations with VT ablations (age, 56.5±17.6; 60.1% men), AEs were reported in 825 (8.5%), major AEs in 295 (3.0%), and death in 110 (1.1%). Heart failure had the strongest association with death (odds ratio, 5.52; 95% confidence interval, 2.97-10.3) and major AE (odds ratio, 2.99; 95% confidence interval, 2.15-4.16). Anemia (odds ratio, 4.84; 95% confidence interval, 3.79-6.19) and unscheduled admission (odds ratio, 1.64; 95% confidence interval, 1.37-1.97) were associated with AEs. During the study period, incidence of AEs increased from 9.2% to 12.8% as did the burden of AE risk factors (0.034 patient/y; P<0.001). Hospital volume >25 cases/y was associated with fewer AEs compared with lower volume centers (6.4% versus 8.8%; P=0.008).VT ablation-associated AE rates in clinical practice are similar to those reported in the literature. Over time rates have increased as have the number of AE risk factors per patient. Ablations done electively and at hospitals with higher procedural volume are associated with lower incidence of AEs.
View details for DOI 10.1161/CIRCEP.114.002336
View details for PubMedID 25688143
- Safety of Ventricular Tachycardia Ablation in Clinical Practice Findings from 9699 Hospital Discharge Records CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY 2015; 8 (2): 362-U153
Correlates and outcomes of warfarin initiation in kidney transplant recipients newly diagnosed with atrial fibrillation.
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association
2015; 30 (2): 321-329
In the kidney transplant population with atrial fibrillation (AF), evidence regarding the effectiveness and safety of warfarin treatment is lacking. We used fee-for-service Medicare claims to identify kidney transplant recipients with newly diagnosed AF from the United States Renal Data System. Warfarin use within 30 days of AF diagnosis was ascertained from Medicare Part D prescription claims (2007-11) or using a validated algorithm (1997-2011). The study end points were (i) the composite of death, stroke or gastrointestinal bleed, (ii) death and (iii) death-censored graft failure. Warfarin user and non-user groups were balanced using inverse probability of treatment weighting and hazard ratios were (HRs) estimated using Cox regression. Among 718 subjects with an indication for anticoagulation, 24% initiated warfarin treatment within 30 days of AF diagnosis. Age was the only independent correlate of warfarin use [odds ratio = 1.02 per year; 95% confidence interval (95% CI) 1.01-1.04]. In the larger cohort of 6492 patients with AF, warfarin use [(23.5%) versus non-use (76.5%)] was associated with small and non-significant reductions in the composite of death, stroke or gastrointestinal bleed (HR = 0.92; 95% CI 0.83-1.02), death (HR = 0.92; 95% CI 0.82-1.02) and death-censored graft failure (HR = 0.90; 95% CI 0.76-1.08). Our study suggests the need for clinical trials of warfarin use in the kidney transplant population with AF.
View details for DOI 10.1093/ndt/gfu323
View details for PubMedID 25335507
- Diagnostic yield of extenced cardiac patch monitoring in patients with stroke or TIA FRONTIERS IN NEUROLOGY 2015; 5
Effectiveness of a community screening program for metabolic syndrome and cardiovascular risk factor identification in young South Asians adults.
Diabetes & metabolic syndrome
2015; 9 (1): 38-41
Metabolic syndrome has been associated with increased risk of cardiovascular disease. We aimed to determine the effectiveness of a community-based screening program in identifying cardiovascular risk factors in healthy young South Asian population.Between 2006 and 2011, 3314 patients of all ages were recruited as a part of a prospective cohort study investigating cardiovascular risk in South Asians. We analyzed 1537 patients between the ages of 18 and 40. Demographic and baseline characteristics including baseline laboratory markers and blood pressures were obtained at initial visit.The total cohort of 1537 patients was 66.5% male, and the mean age was 35±5 years. Among participants who denied a history of hypercholesterolemia, 62% had elevated LDL-C (>100mg/dL), and 8% had markedly elevated LDL-C (>160mg/dL). Overall, diabetes was present in 4%, hypertension was present in 12% and hyperlipidemia was present in 46%. Low HDL-C (50% of men, 52% of women) and elevated triglycerides (44% of men, 18% of women) were the most prevalent components of metabolic syndrome. Metabolic syndrome was present in 14% of men and 8% of women and one-third (30%) of men and one-fifth (19%) of women had at least two component risk factors.This is the largest study to date assessing effectiveness of a community based screening program aiming to identify cardiovascular risk in young South Asians. We note significant modifiable risk at a young age. Such community based interventions can be effective at detecting and managing risk factors early in this vulnerable population.
View details for DOI 10.1016/j.dsx.2014.04.025
View details for PubMedID 25470638
Get With The Guidelines AFIB: novel quality improvement registry for hospitalized patients with atrial fibrillation.
Circulation. Cardiovascular quality and outcomes
2014; 7 (5): 770-777
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It is a cause of stroke, heart failure, and death. Guideline-based treatment can improve outcomes in AF. Unfortunately, adherence to these guidelines is low. Get With The Guidelines is a hospital-based performance initiative, which has been shown to improve adherence over time. Get With The Guidelines-AFIB is a novel quality improvement registry designed to improve adherence to AF guidelines.Hospitals will be recruited by regional American Heart Association staff and key stakeholders. Inpatients or observed patients with AF or atrial flutter will be enrolled. Data collected will include demographic, medical history, and clinical characteristics including laboratory values and treatments. Decision support will guide adherence to achievement and quality measures designed to improve adherence to anticoagulation, heart rate control, safe antiarrhythmic drug use, and patient education and follow-up. Increased adherence to guidelines will be facilitated using rapid-cycle quality improvement, site-specific reporting including national and regional benchmarks and hospital recognition for achievement. Primary analyses will include adherence to American Heart Association/American College of Cardiology performance measures and guidelines. Secondary analyses will include processes of care, risk stratification, treatment of special conditions or populations and use of particular treatment techniques.AF is common clinical problem with significant morbidity and mortality. Get With The Guidelines-AFIB is a national hospital-based AF quality improvement program designed to increase adherence to evidence-based guidelines for AF.
View details for DOI 10.1161/CIRCOUTCOMES.114.001263
View details for PubMedID 25185244
Association between success rate and citation count of studies of radiofrequency catheter ablation for atrial fibrillation: possible evidence of citation bias.
Circulation. Cardiovascular quality and outcomes
2014; 7 (5): 687-692
The preferential citation of studies with the highest success rates could exaggerate perceived effectiveness, particularly for treatments with widely varying published success rates such as radiofrequency catheter ablation for atrial fibrillation.We systematically identified observational studies and clinical trials of radiofrequency catheter ablation of atrial fibrillation between 1990 and 2012. Generalized Poisson regression was used to estimate association between study success rate and total citation count, adjusting for sample size, journal impact factor, time since publication, study design, and whether first or last author was a consensus-defined pre-eminent expert. We identified 174 articles meeting our inclusion criteria (36 289 subjects). After adjustment only for time since publication, a 10-point increase above the mean in pooled reported success rates was associated with a 17.8% increase in citation count at 5 years postpublication (95% confidence interval, 7.1-28.4%; P<0.001). After additional adjustment for impact factor, sample size, randomized trial design, and pre-eminent expert authorship, the association remained significant (18.6% increase in citation count; 95% confidence interval, 7.6-29.6%; P<0.0001). In this full model, time since publication, impact factor, and pre-eminent expert authorship were significant covariates, whereas randomized control trial design and study sample size were not.Among studies of radiofrequency catheter ablation of atrial fibrillation, high success rate was independently associated with citation count, which may indicate citation bias. To readers of the literature, radiofrequency catheter ablation of atrial fibrillation could be perceived to be more effective than the data supports. These findings may have implications for a wide variety of novel cardiovascular therapies.
View details for DOI 10.1161/CIRCOUTCOMES.114.000912
View details for PubMedID 25205786
- Get With The Guidelines AFIB Novel Quality Improvement Registry for Hospitalized Patients With Atrial Fibrillation CIRCULATION-CARDIOVASCULAR QUALITY AND OUTCOMES 2014; 7 (5): 770-777
Adherence to dabigatran therapy and longitudinal patient outcomes: Insights from the Veterans Health Administration
AMERICAN HEART JOURNAL
2014; 167 (6): 810-817
Dabigatran is a novel oral anti-coagulant (NOAC) that reduces risk of stroke in patients with non-valvular atrial fibrillation (NVAF). It does not require routine monitoring with laboratory testing which may have an adverse impact on adherence. We aimed to describe adherence to dabigatran in the first year after initiation and assess the association between non-adherence to dabigatran and clinical outcomes in a large integrated healthcare system.We studied a national cohort of 5,376 patients with NVAF, initiated on dabigatran between October-2010 and September-2012 at all Veterans Affairs hospitals. Adherence to dabigatran was calculated as proportion of days covered (PDC) and association between PDC and outcomes was assessed using standard regression techniques.Mean age of the study cohort was 71.3 ± 9.7 years; 98.3% were men and mean CHADS2 score was 2.4 ± 1.2 (mean CHA2DS2VASc score 3.2 ± 1.4). Median PDC was 94% (IQR 76%-100%; mean PDC 84% ± 22%) over a median follow-up of 244 days (IQR 140-351). A total of 1,494 (27.8%) patients had a PDC <80% and were classified as non-adherent. After multivariable adjustment, lower adherence was associated with increased risk for combined all-cause mortality and stroke (HR 1.13, 95% CI 1.07-1.19 per 10% decrease in PDC). Adherence to dabigatran was not associated with non-fatal bleeding or myocardial infarction.In the year after initiation, adherence to dabigatran for a majority of patients is very good. However, 28% of patients in our cohort had poor adherence. Furthermore, lower adherence to dabigatran was associated with increased adverse outcomes. Concerted efforts are needed to optimize adherence to NOACs.
View details for DOI 10.1016/j.ahj.2014.03.023
View details for Web of Science ID 000338350800009
View details for PubMedID 24890529
Relation of Left Atrial Dysfunction to Ischemic Stroke in Patients With Coronary Heart Disease (from the Heart and Soul Study).
American journal of cardiology
2014; 113 (10): 1679-1684
This study sought to determine whether left atrial (LA) dysfunction independently predicts ischemic stroke. Atrial fibrillation (AF) impairs LA function and is associated with ischemic stroke. However, ischemic stroke frequently occurs in patients without known AF. The direct relation between LA function and risk of ischemic stroke is unknown. We performed transthoracic echocardiography at rest in 983 subjects with stable coronary heart disease. To quantify LA dysfunction, we used the left atrial function index (LAFI), a validated formula incorporating LA volumes at end-atrial systole and diastole. Cox proportional hazards models were used to evaluate the association between LAFI and ischemic stroke or transient ischemic attack (TIA). Over a mean follow-up of 7.1 years, 58 study participants (5.9%) experienced an ischemic stroke or TIA. In patients without known baseline AF or warfarin therapy (n = 893), participants in the lowest quintile of LAFI had >3 times the risk of ischemic stroke or TIA (hazard ratio 3.3, 95% confidence interval 1.1 to 9.7, p = 0.03) compared with those in the highest quintile. For each standard deviation (18.8 U) decrease in LAFI, the hazard of ischemic stroke or TIA increased by 50% (hazard ratio 1.5, 95% confidence interval 1.0 to 2.1, p = 0.04). Among measured echocardiographic indexes of LA function, including LA volume, LAFI was the strongest predictor of ischemic stroke or TIA. In conclusion, LA dysfunction is an independent risk factor for stroke or TIA, even in patients without baseline AF.
View details for DOI 10.1016/j.amjcard.2014.02.021
View details for PubMedID 24792737
Association of CHADS2, CHA2DS2-VASc, and R2CHADS2 Scores With Left Atrial Dysfunction in Patients With Coronary Heart Disease (from the Heart and Soul Study).
American journal of cardiology
2014; 113 (7): 1166-1172
The predictive ability of the CHADS2 index to stratify stroke risk may be mechanistically linked to severity of left atrial (LA) dysfunction. This study investigated the association between the CHADS2 score and LA function. We performed resting transthoracic echocardiography in 970 patients with stable coronary heart disease and normal ejection fraction and calculated baseline LA functional index (LAFI) using a validated formula: (LA emptying fraction×left ventricular outflow tract velocity time integral)/LA end-systolic volume indexed to body surface area. We performed regression analyses to evaluate the association between risk scores and LAFI. Among 970 subjects, mean CHADS2 was 1.7±1.2. Mean LAFI decreased across tertiles of CHADS2 (42.8±18.1, 37.8±19.1, 36.7±19.4, p<0.001). After adjustment for age, sex, race, systolic blood pressure, hyperlipidemia, myocardial infarction, revascularization, body mass index, smoking, and alcohol use, high CHADS2 remained associated with the lowest quartile of LAFI (odds ratio 2.34, p=0.001). In multivariable analysis of component co-morbidities, heart failure, age, and creatinine clearance<60 ml/min were strongly associated with LA dysfunction. For every point increase in CHADS2, the LAFI decreased by 4.0%. Secondary analyses using CHA2DS2-VASc and R2CHADS2 scores replicated these results. Findings were consistent when excluding patients with baseline atrial fibrillation. In conclusion, CHADS2, CHA2DS2-VASc, and R2CHADS2 scores are associated with LA dysfunction, even in patients without baseline atrial fibrillation. These findings merit further study to determine the role of LA dysfunction in cardioembolic stroke and the value of LAFI for risk stratification.
View details for DOI 10.1016/j.amjcard.2013.12.028
View details for PubMedID 24507169
Clinical reminders to providers of patients with reduced left ventricular ejection fraction increase defibrillator referral: a randomized trial.
Circulation. Heart failure
2014; 7 (1): 140-145
Background- Many patients who are candidates for implantable cardioverter defibrillators (ICDs) are not referred for potential implantation. We sought to determine if a simple provider reminder would increase referrals. Methods and Results- We identified consecutive patients from January 2007 through July 2010 in the VA Palo Alto Health Care System with a left ventricular ejection fraction <35% on echocardiography. Patients were excluded using available administrative data only (no chart review) if they were known to have an ICD, if they were ≥80 years old, or if they did not have a current primary care or cardiology provider within the system. We randomized patients to no intervention or a clinical note to the provider in the medical record. The outcomes were referral for consideration of defibrillator implantation (primary) and documented discussion (secondary). Of 330 patients with left ventricular ejection fraction ≤35%, 128 were known to have an ICD, 85 were no longer followed in the healthcare system, and 28 were ≥80 years old, leaving 89 patients to be randomized. Forty-six patients were randomized to intervention and 43 to control. Eleven of 46 (24%) intervention patients were referred for consideration of ICD implantation during the following 6 months versus 1 of 43 (2%) control patients (P=0.004). Overall, 31 of 46 (67%) intervention patients versus 19 of 43 (44%) control patients had documentation discussing potential candidacy for defibrillators (P=0.05). Conclusions- In patients with low left ventricular ejection fraction, a simple electronic medical record-based intervention directed to their providers improved the rates of referral for ICD implantation. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT01217827.
View details for DOI 10.1161/CIRCHEARTFAILURE.113.000753
View details for PubMedID 24319096
- Regarding "feasibility and safety of same-day discharge after implantable cardioverter defibrillator placement for primary prevention". Pacing and clinical electrophysiology : PACE 2014; 37 (1): 131-?
- Phenytoin toxicity unlikely to result in arrhythmias-reply. JAMA internal medicine 2014; 174 (1): 167-168
Diagnostic Yield of Extended Cardiac Patch Monitoring in Patients with Stroke or TIA.
Frontiers in neurology
2014; 5: 266-?
It is important to evaluate patients with transient ischemic attack (TIA) or stroke for atrial fibrillation (AF) because the detection of AF changes the recommended anti-thrombotic regimen from treatment with an antiplatelet agent to oral anticoagulation. This study describes the diagnostic yield of a patch-based, single-use, and water-resistant 14-day continuous cardiac rhythm monitor (ZIO Patch) in patients with stroke or TIA.We obtained data from the manufacturer and servicer of the ZIO Patch (iRhythm Technologies). Patients who were monitored between January 2012 and June 2013 and whose indication for monitoring was TIA or stroke were included. The duration of monitoring, the number and type of arrhythmias, and the time to first arrhythmia were documented.One thousand one hundred seventy-one monitoring reports were analyzed. The mean monitor wear time was 10.9 days and the median wear time was 13.0 days (interquartile range 7.2-14.0). The median analyzable time relative to the total wear time was 98.7% (IQR 96.0-99.5%). AF was present in 5.0% of all reports. The mean duration before the first episode of paroxysmal AF (PAF) was 1.5 days and the median duration was 0.4 days. 14.3% of first PAF episodes occurred after 48 h. The mean PAF burden was 12.7% of the total monitoring duration.Excellent quality of the recordings and very good patient compliance coupled with a substantial proportion of AF detection beyond the first 48 h of monitoring suggest that the cardiac patch is superior to conventional 48-h Holter monitors for AF detection in patients with stroke or TIA.
View details for DOI 10.3389/fneur.2014.00266
View details for PubMedID 25628595
Adherence and persistence in the use of warfarin after hospital discharge among patients with heart failure and atrial fibrillation.
Journal of cardiac failure
2014; 20 (1): 23-30
Postdischarge adherence and long-term persistence in the use of warfarin among patients with heart failure and atrial fibrillation without contraindications have not been fully described.We identified patients with heart failure and atrial fibrillation who were ≥65 years old, eligible for warfarin, and discharged home from hospitals in the Get With the Guidelines-Heart Failure registry from January 1, 2006, to December 31, 2009. We used linked Medicare prescription drug event data to measure adherence and persistence. The main outcome measures were rates of prescription at discharge, outpatient dispensing, discontinuation, and adherence as measured by the medication possession ratio. We hypothesized that adherence to warfarin would differ according to whether patients received the prescription at discharge. Among 2,691 eligible patients, 1,856 (69.0%) were prescribed warfarin at discharge. Patients prescribed warfarin at discharge had significantly higher prescription fill rates within 90 days (84.5% vs 12.3%; P < .001) and 1 year (91.6% vs 16.8%; P < .001) and significantly higher medication possession ratios (0.78 vs 0.63; P < .001). Among both previous nonusers and existing users, fill rates at 90 days and 1 year and possession ratios were significantly higher among those prescribed warfarin at discharge.One-third of eligible patients with heart failure and atrial fibrillation were not prescribed warfarin at discharge from a heart failure hospitalization, and few started therapy as outpatients. In contrast, most patients who were prescribed warfarin at discharge filled the prescription within 90 days and remained on therapy at 1 year.
View details for DOI 10.1016/j.cardfail.2013.11.006
View details for PubMedID 24275703
Diagnostic utility of a novel leadless arrhythmia monitoring device.
American journal of cardiology
2013; 112 (4): 520-524
Although extending the duration of ambulatory electrocardiographic monitoring beyond 24 to 48 hours can improve the detection of arrhythmias, lead-based (Holter) monitors might be limited by patient compliance and other factors. We, therefore, evaluated compliance, analyzable signal time, interval to arrhythmia detection, and diagnostic yield of the Zio Patch, a novel leadless, electrocardiographic monitoring device in 26,751 consecutive patients. The mean wear time was 7.6 ± 3.6 days, and the median analyzable time was 99% of the total wear time. Among the patients with detected arrhythmias (60.3% of all patients), 29.9% had their first arrhythmia and 51.1% had their first symptom-triggered arrhythmia occur after the initial 48-hour period. Compared with the first 48 hours of monitoring, the overall diagnostic yield was greater when data from the entire Zio Patch wear duration were included for any arrhythmia (62.2% vs 43.9%, p <0.0001) and for any symptomatic arrhythmia (9.7% vs 4.4%, p <0.0001). For paroxysmal atrial fibrillation (AF), the mean interval to the first detection of AF was inversely proportional to the total AF burden, with an increasing proportion occurring after 48 hours (11.2%, 10.5%, 20.8%, and 38.0% for an AF burden of 51% to 75%, 26% to 50%, 1% to 25%, and <1%, respectively). In conclusion, extended monitoring with the Zio Patch for ≤14 days is feasible, with high patient compliance, a high analyzable signal time, and an incremental diagnostic yield beyond 48 hours for all arrhythmia types. These findings could have significant implications for device selection, monitoring duration, and care pathways for arrhythmia evaluation and AF surveillance.
View details for DOI 10.1016/j.amjcard.2013.04.017
View details for PubMedID 23672988
Outcomes after kidney transplantation of patients previously diagnosed with atrial fibrillation.
American journal of transplantation
2013; 13 (6): 1566-1575
Little is known about the prevalence and outcomes of patients with atrial fibrillation/flutter (AF) who receive a kidney transplant. We identified all patients who had >1 year of uninterrupted Medicare A+B coverage before receiving their first kidney transplant (1997-2009). The presence of pretransplant AF was ascertained from diagnosis codes in Medicare physician claims. We studied the posttransplant outcomes of death, all-cause graft failure, death-censored graft failure and stroke using multivariable Cox regression. Of 62 706 eligible first kidney transplant recipients studied, 3794 (6.4%) were diagnosed with AF prior to kidney transplant. Over a mean follow up of 4.9 years, 40.6% of AF patients and 24.9% without AF died. All-cause and death-censored graft failure were 46.8% and 16.5%, respectively, in the AF group and 36.4% and 19.5%, respectively, in those without AF. Ischemic stroke occurred in 2.8% of patients with and 1.6% of patients without AF. In patients with AF, multivariable-adjusted hazard ratios (95% confidence intervals) for death, graft failure, death-censored graft failure and ischemic stroke were 1.46 (1.38-1.54), 1.41 (1.34-1.48), 1.26 (1.15-1.37) and 1.36 (1.10-1.68), respectively. Pre-existing AF is associated with poor posttransplant outcomes. Special attention should be paid to AF in pretransplant evaluation, counseling and risk stratification of kidney transplant candidates.
View details for DOI 10.1111/ajt.12197
View details for PubMedID 23721555
- Comparative effectiveness of antiarrhythmic drugs on cardiovascular hospitalization and mortality in atrial fibrillation JOURNAL OF COMPARATIVE EFFECTIVENESS RESEARCH 2013; 2 (3): 301-312
- Foreword: health policy and cardiac electrophysiology JOURNAL OF INTERVENTIONAL CARDIAC ELECTROPHYSIOLOGY 2013; 36 (2): 97-97
- Bizarre and Wide QRS After Liver Transplant. JAMA internal medicine 2013: 1
- Oral Antithrombotic Agents for the Prevention of Stroke in Nonvalvular Atrial Fibrillation A Science Advisory for Healthcare Professionals From the American Heart Association/American Stroke Association STROKE 2012; 43 (12): 3442-3453
Trends in the Incidence of Atrial Fibrillation in Older Patients Initiating Dialysis in the United States
2012; 126 (19): 2293-?
One sixth of US dialysis patients 65 years of age have been diagnosed with atrial fibrillation/flutter (AF). Little is known, however, about the incidence of AF in this population.We identified 258 605 older patients (≥67 years of age) with fee-for-service Medicare initiating dialysis in 1995 to 2007, who had not been diagnosed with AF within the previous 2 years. Patients were followed for newly diagnosed AF. Multivariable proportional hazard regression was used to examine temporal trends and associations of race and ethnicity with incident AF. We also studied temporal trends in the mortality and risk of ischemic stroke after new AF. Over 514 395 person-years of follow-up, 76 252 patients experienced incident AF for a crude AF incidence rate of 148/1000 person-years. Incidence of AF increased by 11% (95% confidence interval, 5-16) from 1995 to 2007. Compared with non-Hispanic whites, blacks (-30%), Asians (-19%), Native Americans (-42%), and Hispanics (-29%) all had lower rates of incident AF. Mortality after incident AF decreased by 22% from 1995 to 2008. Even more pronounced reductions were seen for incident ischemic stroke during these years.The incidence of AF is high in older patients initiating dialysis in the United States and has been increasing over the 13 years of study. Mortality declined during that time but remained >50% during the first year after newly diagnosed AF. Because data on warfarin use were not available, we were unable to study whether trends toward better outcomes could be explained by higher rates of oral anticoagulation.
View details for Web of Science ID 000310744100010
View details for PubMedID 23032326
Anticoagulation for atrial fibrillation in patients on dialysis: are the benefits worth the risks?
CURRENT OPINION IN NEPHROLOGY AND HYPERTENSION
2012; 21 (6): 600-606
Atrial fibrillation is common among patients with end-stage renal disease undergoing hemodialysis. Although oral anticoagulation is recommended for stroke prevention in most patients with atrial fibrillation, limited evidence is available to guide treatment in hemodialysis patients with this arrhythmia. We summarize the available evidence on the epidemiology of atrial fibrillation in dialysis patients and review the data on the effectiveness of oral anticoagulation in this population.Atrial fibrillation is increasingly common in patients undergoing chronic hemodialysis, especially among older patients wherein one in six patients is diagnosed with this arrhythmia. Patients with atrial fibrillation experience double the mortality of otherwise similar patients without it. Few hemodialysis patients with atrial fibrillation receive oral anticoagulation, which is consistently associated with excess risks of hemorrhagic stroke. Observational studies did not detect a beneficial association of oral anticoagulation with the risk of ischemic stroke, with some studies describing higher risks of ischemic stroke among warfarin users. New therapeutic options including one oral direct thrombin inhibitor and two oral factor Xa inhibitors have become available, but were not tested in patients with advanced kidney disease.Atrial fibrillation is increasingly common in patients undergoing hemodialysis, yet little is known about the optimal management of these patients. The current evidence does not support net benefits from oral anticoagulation in the dialysis population.
View details for DOI 10.1097/MNH.0b013e32835856fd
View details for Web of Science ID 000310061500006
View details for PubMedID 23079746
- Reply: Ability of microvolt T-wave alternans to modify risk assessment of ventricular tachyarrhythmic events: A meta-analysis AMERICAN HEART JOURNAL 2012; 164 (4)
- Latency of ECG Displays of Hospital Telemetry Systems A Science Advisory From the American Heart Association CIRCULATION 2012; 126 (13): 1665-1669
- Abrupt bradycardia and grouped beating during treadmill testing: A mimic of upper rate behavior HEART RHYTHM 2012; 9 (7): 1165-1167
Incidence and clinical predictors of low defibrillation safety margin at time of implantable defibrillator implantation
JOURNAL OF INTERVENTIONAL CARDIAC ELECTROPHYSIOLOGY
2012; 34 (1): 93-100
Determination of the defibrillation safety margin (DSM) is the most common method of testing device effectiveness at the time of implantation of implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRTD). Low DSM remains a problem in clinical practice.The purpose of this study is to ascertain the incidence and clinical predictors of low DSM and the treatment strategies for low DSM in ICD or CRTD recipients.Selected ICD or CRTD recipients from January 2006 to May 2008 who underwent DSM test at the time of implantation were included. Low DSM patients were defined as patients who had a DSM within 10 J of the maximum delivered energy of the device. These patients were compared to patients who had DSM > 10 J.This study included 243 patients. Of these, 13 (5.3%) patients had low DSM, and 230 patients had adequate DSM. Patients with low DSM had a high prevalence of amiodarone use (69% vs 13%, p < 0.01), secondary prevention indications (69% vs 30%, p < 0.01), and a trend toward younger age (51 ± 18 vs 58 ± 15 years, p = 0.08). After adjustment for age and sex, amiodarone use was significantly associated with low DSM. All low DSM patients except one obtained adequate DSM after taking additional steps, including discontinuing amiodarone and starting sotalol, RV lead repositioning, adding a subcutaneous array or shock coil, changing single-coil to dual-coil lead, and upgrading to a high output device.The incidence of low DSM patients is low with high-energy devices. Amiodarone use is associated with low DSM, and its discontinuation or substitution with sotalol is one of a variety of available options for low DSM patients.
View details for DOI 10.1007/s10840-011-9648-z
View details for Web of Science ID 000303541200013
View details for PubMedID 22391960
TRENDS IN THE INCIDENCE OF ATRIAL FIBRILLATION IN OLDER PATIENTS INITIATING DIALYSIS IN THE UNITED STATES
49th Congress of the European-Renal-Association/European-Dialysis-and-Transplant-Association (ERA-EDTA)
OXFORD UNIV PRESS. 2012: 231–232
View details for Web of Science ID 000311494700635
The prognostic value of early repolarization with ST-segment elevation in African Americans
2012; 9 (4): 558-565
Increased prevalence of classic early repolarization, defined as ST-segment elevation (STE) in the absence of acute myocardial injury, in African Americans is well established. The prognostic value of this pattern in different ethnicities remains controversial.Measure association between early repolarization and cardiovascular mortality in African Americans.The resting electrocardiograms of 45,829 patients were evaluated at the Palo Alto Veterans Affairs Hospital. Subjects with inpatient status or electrocardiographic evidence of acute myocardial infarction were excluded, leaving 29,281 subjects. ST-segment elevation, defined as an elevation of >0.1 mV at the end of the QRS, was electronically flagged and visually adjudicated by 3 observers blinded to outcomes. An association between ethnicity and early repolarization was measured by using multivariate logistic regression. We analyzed associations between early repolarization and cardiovascular mortality by using the Cox proportional hazards regression analysis.Subjects were 13% women and 13.3% African Americans, with an average age of 55 years and followed for an average of 7.6 years, resulting in 1995 cardiovascular deaths. There were 479 subjects with lateral STE and 185 with inferior STE. After adjustment for age, sex, heart rate, and coronary artery disease, African American ethnicity was associated with lateral or inferior STE (odds ratio 3.1; P = .0001). While lateral or inferior STE in non-African Americans was independently associated with cardiovascular death (hazard ratio 1.6; P = .02), it was not associated with cardiovascular death in African Americans (hazard ratio 0.75; P = .50).Although early repolarization is more prevalent in African Americans, it is not predictive of cardiovascular death in this population and may represent a distinct electrophysiologic phenomenon.
View details for DOI 10.1016/j.hrthm.2011.11.020
View details for Web of Science ID 000302258100020
View details for PubMedID 22094072
AMIODARONE USE IS NOT ASSOCIATED WITH MORTALITY IN PATIENTS WITH ATRIAL FIBRILLATION AND KIDNEY DYSFUNCTION OR DIALYSIS: THE TREAT-AF STUDY
61st Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC)/Conference on ACC-i2 with TCT
ELSEVIER SCIENCE INC. 2012: E682–E682
View details for Web of Science ID 000302326700684
CARDIOVASCULAR HOSPITALIZATION IS A STRONG PREDICTOR OF MORTALITY IN MEDICARE BENEFICIARIES WITH NEWLY DIAGNOSED ATRIAL FIBRILLATION
61st Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC)/Conference on ACC-i2 with TCT
ELSEVIER SCIENCE INC. 2012: E723–E723
View details for Web of Science ID 000302326700724
INTERACTION AMONG DIGOXIN USE, KIDNEY FUNCTION, AND MORTALITY IN PATIENTS WITH ATRIAL FIBRILLATION: THE TREAT-AF STUDY
61st Annual Scientific Session and Expo of the American-College-of-Cardiology (ACC)/Conference on ACC-i2 with TCT
ELSEVIER SCIENCE INC. 2012: E685–E685
View details for Web of Science ID 000302326700687
Ability of microvolt T-wave alternans to modify risk assessment of ventricular tachyarrhythmic events: A meta-analysis
AMERICAN HEART JOURNAL
2012; 163 (3): 354-364
Prior studies have indicated that the magnitude of risk association of microvolt T-wave alternans (MTWA) testing appears to vary with the population studied. We performed a meta-analysis to determine the ability of MTWA to modify risk assessment of ventricular tachyarrhythmic events (VTEs) and sudden cardiac death (SCD) across a series of patient risk profiles using likelihood ratio (LR) testing, a measure of test performance independent of disease prevalence.We identified original research articles published from January 1990 to January 2011 that investigate spectrally derived MTWA. Ventricular tachyarrhythmic event was defined as the total and arrhythmic mortality and nonfatal sustained or implantable cardioverter-defibrillator-treated ventricular tachyarrhythmias. Summary estimates were created for positive and nonnegative MTWA results using a random-effects model and were expressed as positive (LR+) and negative (LR-) LRs.Of 1,534 articles, 20 prospective cohort studies met our inclusion criteria, consisting of 5,945 subjects predominantly with prior myocardial infarction or left ventricular dysfunction. Although there was a modest association between positive MTWA and VTE (relative risk 2.45, 1.58-3.79) and nonnegative MTWA and VTE (3.68, 2.23-6.07), test performance was poor (positive MTWA: LR+ 1.78, LR- 0.43; nonnegative MTWA: LR+ 1.38, LR- 0.56). Subgroup analyses of subjects classified as prior VTE, post-myocardial infarction, SCD-HeFT type, and MADIT-II type had a similar poor test performance. A negative MTWA result would decrease the annualized risk of VTE from 8.85% to 6.37% in MADIT-II-type patients and from 5.91% to 2.60% in SCD-HeFT-type patients.Despite a modest association, results of spectrally derived MTWA testing do not sufficiently modify the risk of VTE to change clinical decisions.
View details for DOI 10.1016/j.ahj.2011.11.021
View details for Web of Science ID 000301597200010
View details for PubMedID 22424005
Left Atrial Function Predicts Heart Failure Hospitalization in Subjects With Preserved Ejection Fraction and Coronary Heart Disease Longitudinal Data From the Heart and Soul Study
JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
2012; 59 (7): 673-680
This study sought to determine whether left atrial (LA) dysfunction predicts heart failure (HF) hospitalization in subjects with preserved baseline ejection fraction (EF).Among patients with preserved EF, factors leading to HF are not fully understood. Cross-sectional studies have demonstrated LA dysfunction at the time of HF, but longitudinal data on antecedent atrial function are lacking.We performed resting transthoracic echocardiography in 855 subjects with coronary heart disease and EF ≥50%. Left atrial functional index (LAFI) was calculated as ([LA emptying fraction × left ventricular outflow tract-velocity time integral] / [indexed LA end-systolic volume]), where LA emptying fraction was defined as (LA end-systolic volume--LA end-diastolic volume) / LA end-systolic volume. We used Cox models to evaluate the association between LAFI and HF hospitalization.Over a median follow-up of 7.9 years, 106 participants (12.4%) were hospitalized for HF. Rates of HF hospitalization were inversely proportional to quartile (Q) of LAFI: Q1, 47 per 1,000 person-years; Q2, 18.3; Q3, 9.6; and Q4, 5.3 (p < 0.001). Each standard deviation decrease in LAFI was associated with a 2.6-fold increased hazard of adverse cardiovascular outcomes (unadjusted hazard ratio: 2.6, 95% confidence interval: 2.1 to 3.3, p < 0.001), and the association persisted even after adjustment for clinical risk factors, N-terminal pro-B-type natriuretic peptide, and a wide range of echocardiographic parameters (adjusted hazard ratio: 1.5, 95% confidence interval: 1.0 to 2.1, p = 0.05).Left atrial dysfunction independently predicts HF hospitalization in subjects with coronary heart disease and preserved baseline EF. The LAFI may be useful for HF risk stratification, and LA dysfunction may be a potential therapeutic target.
View details for DOI 10.1016/j.jacc.2011.11.012
View details for Web of Science ID 000300393900008
View details for PubMedID 22322084
Cost-effectiveness of pharmacologic and invasive therapies for stroke prophylaxis in atrial fibrillation
JOURNAL OF CARDIOVASCULAR MEDICINE
2012; 13 (2): 86-96
Atrial fibrillation is an abnormal heart rhythm characterized by rapid, disorganized activation (fibrillation) of the left and right atria of the heart, and is responsible for 15% of 700,000 strokes in the United States each year. There are multiple pharmacologic and nonpharmacologic therapies used for stroke prevention in atrial fibrillation, including vitamin K antagonists such as warfarin, antiplatelet agents such as aspirin and clopidogrel, and newer agents such as dabigatran, rivaroxaban and apixaban. Nonpharmacologic therapies involve excluding the left atrial appendage from the systemic circulation by surgical ligation or excision, percutaneous ligation, or endovascular implantation of a left atrial occlusion device. Because atrial fibrillation-related stroke is preventable, a comparison of the value of these interventions by cost-effectiveness analysis (CEA) could inform clinical and health policy recommendations. In this article, we review the principles of CEA and identify 11 articles that examine CEA of stroke prophylaxis strategies in atrial fibrillation. Although most studies evaluate aspirin and warfarin across a variety of atrial fibrillation stroke risk profiles, we also review new literature on new pharmacologic therapies such as direct thrombin inhibitors and discuss the potential value of device-based therapies.
View details for DOI 10.2459/JCM.0b013e32834f23cf
View details for Web of Science ID 000299652200002
View details for PubMedID 22193838
Clinical Reminders to Providers of Patients with Depressed Left Ventricular Ejection Fraction Increase Defibrillator Implantation: A Randomized Trial
Scientific Sessions of the American-Heart-Association/Resuscitation Science Symposium
LIPPINCOTT WILLIAMS & WILKINS. 2011
View details for Web of Science ID 000299738704068
Early Repolarization in an Ambulatory Clinical Population
2011; 124 (20): 2208-2214
The significance of early repolarization, particularly regarding the morphology of the R-wave downslope, has come under question.We evaluated 29 281 resting ambulatory ECGs from the VA Palo Alto Health Care System. With PR interval as the isoelectric line and amplitude criteria ≥0.1 mV, ST-segment elevation is defined at the end of the QRS, J wave as an upward deflection, and slur as a conduction delay on the QRS downstroke. Associations of ST-segment elevation patterns, J waves, and slurs with cardiovascular mortality were analyzed with Cox analysis. With a median follow-up of 7.6 years, there were 1995 cardiac deaths. Of 29 281 subjects, 87% were male (55±14 years) and 13% were female (56±17 years); 13% were black, 6% were Hispanic, and 81% were white or other. Six hundred sixty-four (2.3%) had inferior or lateral ST-segment elevation: 185 (0.6%) in inferior leads and 479 (1.6%) in lateral leads, 163 (0.6%) in both, and 0.4% had global elevation. A total of 4041 ECGs were analyzed with enhanced display, and 583 (14%) had J waves or slurring, which were more prevalent in those with than in those without ST-segment elevation (61% versus 13%; P<0.001). ST-segment elevation occurred more in those with than in those without J waves or slurs (12% versus 1.3%; P<0.001). Except when involving only inferior leads, all components of early repolarization were more common in young individuals, male subjects, blacks, and those with bradycardia. All patterns and components of early repolarization were associated with decreased cardiovascular mortality, but this was not significant after adjustment for age.We found no significant association between any components of early repolarization and cardiac mortality.
View details for DOI 10.1161/CIRCULATIONAHA.111.047191
View details for Web of Science ID 000297060700013
View details for PubMedID 21986288
JICE goes "social"
JOURNAL OF INTERVENTIONAL CARDIAC ELECTROPHYSIOLOGY
2011; 32 (2): 79-80
Social media is transforming health care. The Journal of Interventional Cardiac Electrophysiology (JICE) has launched its own social media presence and is now on Facebook. JICE will post each issue's table of contents, special articles, online-first publications to allow real-time notifications to JICE's readers and fans of our Facebook page. We encourage you to take the plunge and connect to our Facebook page.
View details for DOI 10.1007/s10840-011-9621-x
View details for Web of Science ID 000297556800001
View details for PubMedID 21972151
The CHADS(2) score predicts ischemic stroke in the absence of atrial fibrillation among subjects with coronary heart disease: Data from the Heart and Soul Study
AMERICAN HEART JOURNAL
2011; 162 (3): 555-561
We sought to evaluate the prognostic performance of the CHADS(2) score for prediction of ischemic stroke/transient ischemic attack (TIA) in subjects with coronary heart disease (CHD) without atrial fibrillation (AF).In 916 nonanticoagulated outpatients with stable CHD and no AF by baseline electrocardiogram, we calculated CHADS(2) scores (congestive heart failure, hypertension, age ≥75 years, diabetes [1 point each], and prior stroke or TIA [2 points]). The primary outcome was time to ischemic stroke or TIA over a mean follow-up of 6.4 ± 2.3 years.Over 5,821 person-years of follow-up, 40 subjects had an ischemic stroke/TIA (rate 0.69/100 person-years, 95% CI 0.50-0.94). Compared with subjects with low (0-1) CHADS(2) scores, those with intermediate (2-3) and high (4-6) CHADS(2) scores had an increased rate of stroke/TIA, even after adjustment for age, tobacco, antiplatelet therapy, statins, and angiotensin inhibitors (CHADS(2) score 2-3: HR 2.4, 95% CI 1.1-5.3, P = .03; CHADS(2) score 4-6: HR 4.0, 95% CI 1.5-10.6, P = .006). Model discrimination (c-statistic = 0.65) was comparable with CHADS(2) model fit in published AF-only cohorts.The CHADS(2) score predicts ischemic stroke/TIA in subjects with stable CHD and no baseline AF. The event rate in non-AF subjects with high CHADS(2) scores (5-6) was comparable with published rates in AF patients with moderate CHADS(2) scores (1-2), a population known to derive benefit from stroke prevention therapies. These findings should inform efforts to determine whether stroke prevention therapies or screening for silent AF may benefit subjects with stable CHD and high CHADS(2) scores.
View details for DOI 10.1016/j.ahj.2011.05.023
View details for Web of Science ID 000294447400022
View details for PubMedID 21884876
Dabigatran Compared With Warfarin for Stroke Prevention in Atrial Fibrillation
ANNALS OF INTERNAL MEDICINE
2011; 154 (8): 570-571
View details for Web of Science ID 000289622000024
- Quality of Stroke Prevention Care in Atrial Fibrillation Many Moving Targets CIRCULATION-CARDIOVASCULAR QUALITY AND OUTCOMES 2011; 4 (1): 5-8
- Using Restriction to Minimize Bias in Observational Studies JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION 2010; 304 (21): 2359-2359
Sudden Cardiac Death and Implantable Cardioverter-Defibrillators
AMERICAN FAMILY PHYSICIAN
2010; 82 (11): 1357-1366
Sudden cardiac death is a major public health problem, affecting 500,000 patients in the United States annually. An implantable cardioverter-defibrillator (ICD) can terminate malignant ventricular arrhythmias and has been shown to improve survival in high-risk populations. Although sudden cardiac death is a heterogeneous condition, left ventricular ejection fraction of 35 percent or less remains the single best factor to stratify patients for prophylactic ICD implantation, and randomized trials have shown mortality benefit in this population. Therefore, in patients with heart disease, assessment of ejection fraction remains the most important step to identify patients at risk of sudden cardiac death who would benefit from ICD implantation. Physician understanding of each patient's ICD type, indication, etiology of heart disease, and cardiovascular status is essential for optimal care. If the ICD was placed for secondary prevention, the circumstances relating to the index event should be explored. Evaluation of defibrillator shocks merits careful assessment of the patient's cardiovascular status. Consultation with a subspecialist and interrogation of the ICD can determine if shocks were appropriate or inappropriate and can facilitate management.
View details for Web of Science ID 000208405500010
Inappropriate Pacing in a Patient with Managed Ventricular Pacing: What Is the Cause?
2010; 7 (12)
View details for Web of Science ID 000284875500003
Prevalence of Metabolic Syndrome in South Asians Residing in the United States
METABOLIC SYNDROME AND RELATED DISORDERS
2010; 8 (5): 417-423
The aim of this study was to define the prevalence of the metabolic syndrome and its component risk factors among individuals of South Asian origin living in the United States.We analyzed baseline data from 1,445 participants enrolled in a cohort study investigating risk factors for cardiovascular disease in South Asians. We defined the metabolic syndrome using the International Diabetes Federation criteria for waist circumference (>90 cm for men; >80 cm, women), triglycerides (>150 mg/dL), high-density lipoprotein cholesterol (HDL-C) (<40 mg/dL (men), < mg/dL (women)), blood pressure (>135/80 mmHg), and fasting glucose (>100 mg/dL).The mean age was 43 +/-10 years, and 30% of participants were women. The prevalence of metabolic syndrome was 27% (31% men vs. 17% women, P < 0.05). Fifty-nine percent of the cohort had high waist circumference (58% men vs. 62% women, P = not significant [N.S.]), 47% had low HDL-C [46% men vs. 48% women (NS)], 19% had elevated triglycerides (23% men vs. 8% women, P < 0.05), 14% had hypertension (16% men vs. 9% women, P < 0.05), and 13% had elevated fasting glucose (18% men vs. 11% women, P < 0.05). The most common metabolic syndrome phenotype is low HDL-C with elevated triglycerides.Although the prevalence of the metabolic syndrome is lower than previous reports of South Asians, the prevalence is still unacceptably high despite the presence of protective demographic factors.
View details for DOI 10.1089/met.2009.0097
View details for Web of Science ID 000282809400006
View details for PubMedID 20939706
Developing the Safety of Atrial Fibrillation Ablation Registry Initiative (SAFARI) as a collaborative pan-stakeholder critical path registry model: A Cardiac Safety Research Consortium "Incubator" Think Tank
AMERICAN HEART JOURNAL
2010; 160 (4): 619-U249
Although several randomized clinical trials have demonstrated the safety and efficacy of catheter ablation of atrial fibrillation (AF) in experienced centers, the outcomes of this procedure in routine clinical practice and in patients with persistent and long-standing persistent AF remain uncertain. Brisk adoption of this therapy by physicians with diverse training and experience highlights potential concerns regarding the safety and effectiveness of this procedure. Some of these concerns could be addressed by a national registry of AF ablation procedures such as the Safety of Atrial Fibrillation Ablation Registry Initiative that was initially proposed at a Cardiac Safety Research Consortium Think Tank meeting in April 2009. In January 2010, the Cardiac Safety Research Consortium, in collaboration with the Duke Clinical Research Institute, the US Food and Drug Administration, the American College of Cardiology, and the Heart Rhythm Society, held a follow-up meeting of experts in the field to review the construct and progress to date. Other participants included the National Heart, Lung, and Blood Institute; the Centers for Medicare and Medicaid Services; the Agency for Healthcare Research and Quality; the AdvaMed AF working group; and additional industry representatives. This article summarizes the discussions that occurred at the meeting of the state of the Safety of Atrial Fibrillation Ablation Registry Initiative, the identification of a clear pathway for its implementation, and the exploration of solutions to potential issues in the execution of this registry.
View details for DOI 10.1016/j.ahj.2010.06.044
View details for Web of Science ID 000282677300010
View details for PubMedID 20934554
Inappropriate pacing in a patient with managed ventricular pacing: What is the cause?
2010; 7 (9): 1336-1337
A case of inappropriate atrial pacing in a patient with a pacemaker programmed with Managed Ventricular Pacing (MVP) mode, a proprietary algorithm in Medtronic devices, is presented. The patient was an 84-year-old woman who presented in sinus rhythm with complete atrioventricular block. A dual-chamber pacemaker was implanted and programmed to an MVP pacing mode. After the implant, the patient developed a relatively slow atrial tachyarrhythmia with 2:1 atrioventricular block and inappropriate atrial pacing, followed by a delay in tracking of the atrial tachyarrhythmia. The mechanisms for these behaviors are described.
View details for DOI 10.1016/j.hrthm.2010.04.028
View details for Web of Science ID 000281444100033
View details for PubMedID 20435165
Predicting Heart Failure Hospitalization and Mortality by Quantitative Echocardiography: Is Body Surface Area the Indexing Method of Choice? The Heart and Soul Study
JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY
2010; 23 (4): 406-413
Echocardiographic measurements of left ventricular (LV) mass, left atrial (LA) volume, and LV end-systolic volume (ESV) predict heart failure (HF) hospitalization and mortality. Indexing measurements by body size is thought to establish limits of normality among individuals varying in body habitus. The American Society of Echocardiography recommends dividing measurements by body surface area (BSA), but others have advocated alternative indexing methods.Echocardiographic measurements were collected in 1024 ambulatory adults with coronary artery disease. LV mass, LA volume, and LV ESV were calculated using truncated ellipse method and biplane method of disk formulae. Comparison between raw measurements and measurements divided by indexing parameters was made by hazard ratios per standard deviation increase in variable and c-statistics for BSA, BSA(0.43), BSA(1.5), height, height(0.25), height(2), height(2.7), body weight (BW), BW(0.26), body mass index (BMI), and BMI(0.27).Mean LV mass was 192 +/- 57 g, mean LA volume was 65 +/- 24 mL, and mean LV ESV was 41 +/- 26 mL. Average height was 171 +/- 9 cm, average BSA was 1.94 +/- 0.22 m(2), and average BMI was 28.4 +/- 5.3 kg/m(2). At an average follow-up of 5.6 +/- 1.8 years, there were 148 HF hospitalizations, 71 cardiovascular (CV) deaths, and 269 all-cause deaths. There was excellent correlation between raw measurements and those indexed by height (r = 0.98-0.99), and moderate correlation between raw measurements and those indexed by BW (r = 0.73-0.94). C-statistics and hazard ratios per standard deviation increase in indexed variables were similar for HF hospitalization, CV mortality, and all-cause mortality. There were no significant differences among indexing methods in ability to predict outcomes.The choice of indexing method by parameters of BSA, height, BW, and BMI does not affect the clinical usefulness of LV mass, LA volume, and LV ESV in predicting HF hospitalization, CV mortality, or all-cause mortality among ambulatory adults with coronary artery disease. Continued use of BSA to index measurements of LV mass, LA volume, and LV ESV is acceptable.
View details for DOI 10.1016/j.echo.2010.01.019
View details for Web of Science ID 000276248600012
View details for PubMedID 20202792
Atrial Mechanical Function Using Left Atrial Pressure Waveform Analysis in Persistent and Paroxysmal Atrial Fibrillation Patients
82nd National Conference and Exhibitions and Scientific Sessions of the American-Heart-Association
LIPPINCOTT WILLIAMS & WILKINS. 2009: S628–S628
View details for Web of Science ID 000271831501532
Increase in end-systolic volume after exercise independently predicts mortality in patients with coronary heart disease: data from the Heart and Soul Study
EUROPEAN HEART JOURNAL
2009; 30 (20): 2478-2484
The predictive value of changes in global left ventricular (LV) size after exercise has not been studied. Left ventricular end-systolic volume (ESV) is a relatively load-independent echocardiographic marker of contractility that is easily measured. We investigated the role of the change in ESV at rest and after peak exercise on mortality among patients with stable coronary heart disease (CHD).We performed exercise treadmill testing with stress echocardiography in 934 ambulatory subjects with CHD. End-systolic volume was measured immediately before and after exercise using 2D echocardiography. We defined ESV reversal as an increase in ESV after exercise, and we examined the association of ESV reversal with all-cause mortality during a median follow-up of 3.92 years. Of the 934 participants, 199 (21%) had ESV reversal. At the end of follow-up, mortality was higher among participants with ESV reversal than those without (26 vs. 11%; P < 0.001). After adjustment for clinical covariates, ESV reversal remained predictive of all-cause mortality (HR 2.0; 95% CI 1.4-2.9; P = 0.001). The association of ESV reversal with mortality also persisted after adjustment for exercise-induced wall-motion abnormalities (HR 1.7; 95% CI 1.1-2.3, P = 0.006). To determine if the effect of ESV reversal was independent from other echocardiographic measurements, we created a separate model adjusting for resting LV ejection fraction, ESV, end-diastolic volume, and LV mass. End-systolic volume reversal was the only significant predictor of mortality in this model (HR 2.1, 95% CI 1.4-3.0, P < 0.001).End-systolic volume reversal is a novel parameter that independently predicts mortality in patients with CHD undergoing exercise treadmill echocardiography, even after adjustment for a wide range of clinical, echocardiographic, and treadmill exercise variables. Because measurement of ESV is simple, reproducible, and requires no additional imaging views, identification of ESV reversal during exercise echocardiography can provide useful complementary information for risk stratification.
View details for DOI 10.1093/eurheartj/ehp270
View details for Web of Science ID 000270985300020
View details for PubMedID 19578167
- "Low ejection fraction prophylaxis" with implantable defibrillators in the elderly: Call for a randomized trial? HEART RHYTHM 2009; 6 (8): 1144-1145
- Polymorphic Ventricular Tachycardia? JOURNAL OF HOSPITAL MEDICINE 2009; 4 (2): 140-141
Rates and severity of perforation from implantable cardioverter-defibrillator leads: A 4-year study
JOURNAL OF INTERVENTIONAL CARDIAC ELECTROPHYSIOLOGY
2009; 24 (1): 47-52
Although recent case reports and one small single-year observational study report a substantially increased rate of perforation with the St. Jude Riata series defibrillator lead, these results have not been externally validated.From 2004 to 2007, 593 implantable cardioverter-defibrillator (ICD) implants were performed by six faculty and 13 fellows at four University of California, San Francisco, CA, USA and affiliate hospitals. An electronic medical records system was systematically searched to identify clinically significant cases of ICD lead dislodgment or perforation. Of 307 (56%) St. Jude leads (all Riata series 6.3- and 7.3-French leads), 188 (29%) Medtronic leads (including 99 Sprint Fidelis 6.6 French leads), and 98 (15%) Guidant/Boston Scientific leads, there were three perforations in 593 cases (0.51%). One perforation occurred with a Medtronic Sprint Fidelis 6949 lead (0.53%), and two with a St. Jude Riata 1581 lead (0.65%). There were no statistically significant differences in perforation or dislodgement rates between manufacturers or lead models (p = NS for all). In both cases of perforation with the St. Jude Riata leads, the lead tip perforated through the pericardium into the pleural space.In our 4-year series of ICD implants, perforation and dislodgement rates were low, similar across all lead makes and models, and well below published and accepted complication rates. Our findings contradict previously-reported higher rates of perforation with the Riata lead. Registry and product performance reports should also classify complications by severity and outcome to provide a more complete assessment of product safety.
View details for DOI 10.1007/s10840-008-9308-0
View details for Web of Science ID 000262987700008
View details for PubMedID 18855128
Wolff-Parkinson-White syndrome: where is the pathway?
Indian pacing and electrophysiology journal
2009; 9 (2): 130-133
A 31-year old male presented with atrial fibrillation and ventricular preexcitation that was positive in leads V1-V4, negative in lead II, and positive in lead AVR. The patient was cardioverted and invasive electrophysiologic study was performed. Based on the ECG findings, the coronary sinus and its branches were interrogated during orthodromic atrioventricular reentrant tachycardia. The earliest local activation was seen in the true coronary sinus lumen at the bifurcation of the posterolateral branch. Radiofrequency energy application at this area led to loss of preexcitation. When localizing left septal and posterior accessory pathways, ventricular preexcitation that is both negative in II and positive in AVR has been shown in previous studies to be highly sensitive and specific for a subepicardial location. Therefore, investigation of the coronary sinus and its branches may allow for effective ablation without the need for left ventricular access.
View details for PubMedID 19308285
Impact of Remote Magnetic Catheter Navigation on Ablation Fluoroscopy and Procedure Time
PACE-PACING AND CLINICAL ELECTROPHYSIOLOGY
2008; 31 (11): 1399-1404
Remote magnetic catheter navigation (RCN) is gaining acceptance in clinical cardiac electrophysiology, but details regarding how RCN affects procedure execution are not well characterized.From January 1, 2005, to November 30, 2007, 721 cases were retrospectively analyzed and compared. Of these, 127 used RCN and 594 used manual catheter navigation (MCN). Data including procedure time, fluoroscopy time, ablation catheter, procedural success, and complications were extracted from our procedure database and compared between RCN and MCN.RCN use significantly decreased fluoroscopy time for atrial fibrillation (AF) ablation (-29 minutes, P < 0.001), atrioventricular nodal reentrant tachycardia ablation (-14 minutes, P < 0.001), and atrioventricular reentrant tachycardia ablation (-18 minutes, P = 0.045). While RCN significantly increased mean procedure time for AF (+36 minutes, P = 0.003) and atypical atrial flutter cases (+116 minutes, P = 0.016), RCN AF procedure time diminished with increasing number of cases performed. Two cases of tamponade occurred during AF ablation using MCN (2.2%, 2 of 91 cases). No tamponade occurred during all 75 AF ablations with RCN.RCN can reduce fluoroscopy time and may reduce complications during catheter ablation. While it may increase total procedure duration, procedure times decrease with increasing operator experience. (PACE 2008; 31:1399-1404).
View details for DOI 10.1111/j.1540-8159.2008.01202.x
View details for Web of Science ID 000262203600005
View details for PubMedID 18950296
Prognostic Significance of Increased Left Ventricular Mass Index to Mortality and Sudden Death in Patients With Stable Coronary Heart Disease (from the Heart and Soul Study)
AMERICAN JOURNAL OF CARDIOLOGY
2008; 102 (9): 1131-1135
Data are limited about the significance of left ventricular (LV) hypertrophy or mass in patients with coronary heart disease (CHD), particularly in the setting of normal ejection fraction (EF). The association of LV mass index with all-cause mortality and sudden death in a cohort with CHD was evaluated. Using transthoracic echocardiography, LV mass normalized to body surface area was measured in 1,016 subjects with stable CHD. Cox proportional hazards models were used to examine the association of LV mass index and LV hypertrophy (LV mass index >95 g/m(2) in women and >115 in men) with time to death and time to sudden or arrhythmic death. Mean LV mass index was 101 +/- 27 g/m(2) in men and 88 +/- 23 in women. During a mean follow-up of 3.55 years, there were 146 deaths and 34 sudden or arrhythmic deaths. Total mortality was higher in subjects with LV hypertrophy (25% vs 11%, p <0.001), as was mortality from sudden or arrhythmic death (6.7% vs 2.2%, p = 0.001). After adjustment for age, gender, cardiovascular risk factors, and medical therapy, LV hypertrophy was associated with both all-cause mortality (hazard ratio 2.0, p <0.001) and sudden or arrhythmic death (hazard ratio 3.1, p = 0.003). Findings were similar in the subgroup with EF > or =55% (mortality hazard ratio 1.8, p = 0.02; sudden and arrhythmic death hazard ratio 3.1, p = 0.02). Analyzed as a continuous variable, every 20-unit increase in LV mass index increased the adjusted hazard of death by 22% (p = 0.001) and adjusted hazard of sudden or arrhythmic death by 40% (p = 0.004). In conclusion, in patients with stable CHD, increased LV mass index was independently associated with all-cause mortality and sudden or arrhythmic death, even in subjects with normal EF.
View details for DOI 10.1016/j.amjcard.2008.06.030
View details for Web of Science ID 000261007500003
View details for PubMedID 18940278
Impact of advanced age on survival in patients with implantable cardioverter defibrillators
2008; 10 (11): 1296-1301
Given the selectivity of clinical trial patients and meager representation of elderly in the major implantable cardioverter defibrillator (ICD) randomized trials (<25%), whether such data apply to elderly patients overall is unclear. The purpose of our study is to understand the influence of age on mortality after ICD implantation.We performed a retrospective cohort study of 502 consecutive patients receiving ICDs from 1993 to 2003 at a single university hospital. The primary predictor was patient age, categorized as <65, 65-75, and >75 years at ICD implantation. The primary outcome was time to death. Mean follow-up was 4 years. Median survival after ICD implantation was 5.3 years among subjects >75 years, less than half that of the youngest group. After adjusting for potential confounders, compared with subjects <65 years of age, patients >75 years [hazard ratio (HR), 4.7; 95% confidence interval (CI), 2.8-7.9; P < 0.001] and those 65-75 years (HR, 2.8; 95% CI, 1.7-4.8; P < 0.001) were at greater risk of death. Increased age was associated with higher total, cardiac, and non-cardiac mortality (all P
View details for DOI 10.1093/europace/eun253
View details for Web of Science ID 000260556300009
View details for PubMedID 18818212
- The Irritable Heart JOURNAL OF HOSPITAL MEDICINE 2008; 3 (5): 423-429
Knowledge and attitudes of primary care physicians in the management of patients at risk for cardiovascular events
BMC FAMILY PRACTICE
Adherence to clinical practice guidelines for management of cardiovascular disease (CVD) is suboptimal. The purposes of this study were to identify practice patterns and barriers among U.S. general internists and family physicians in regard to cardiovascular risk management, and examine the association between physician characteristics and cardiovascular risk management.A case vignette survey focused on cardiovascular disease risk management was distributed to a random sample of 12,000 U.S. family physicians and general internists between November and December 2006.Responses from a total of 888 practicing primary care physicians who see 60 patients per week were used for analysis. In an asymptomatic patient at low risk for cardiovascular event, 28% of family physicians and 37% of general internists made guideline-based preventive choices for no antiplatelet therapy (p < .01). In a patient at high risk for cardiovascular event, 59% of family physicians and 56% of general internists identified the guideline-based goal for serum fasting LDL level (< 100 mg/dl). Guideline adherence was inversely related to years in practice and volume of patients seen. Cost of medications (87.7%), adherence to medications (74.1%), adequate time for counseling (55.7%), patient education tools (47.1%), knowledge and skills to recommend dietary changes (47.8%) and facilitate patient adherence (52.0%) were cited as significant barriers to CVD risk management.Despite the benefits demonstrated for managing cardiovascular risks, gaps remain in primary care practitioners' management of risks according to guideline recommendations. Innovative educational approaches that address barriers may facilitate the implementation of guideline-based recommendations in CVD risk management.
View details for DOI 10.1186/1471-2296-9-42
View details for Web of Science ID 000257836800001
View details for PubMedID 18611255
Sudden cardiac death: Epidemiology, mechanisms, and therapy
CURRENT PROBLEMS IN CARDIOLOGY
2007; 32 (9): 501-546
Sudden cardiac death is a major public health problem affecting 500,000 patients annually in the United States alone. The major risk factor for sudden cardiac death is the presence of coronary artery disease, usually in the setting of reduced ejection fraction. Globally, the incidence is expected to rise sharply as the prevalence of coronary artery disease and heart failure continue to increase. However, sudden cardiac death is a heterogeneous condition and may be caused by acute ischemia, structural defects, myocardial scar, and/or genetic mutations. Sudden death may occur even in a grossly normal heart. Beta-blockers can reduce the risk of sudden cardiac death, while implantable cardioverter defibrillators are effective at terminating malignant arrhythmias. Ejection fraction remains the major criterion to stratify patients for defibrillator implantation but this strategy alone is insensitive and nonspecific. Novel clinical, electrophysiologic, and genetic markers have been identified that may increase precision in patient selection for primary prevention therapy. This review discusses the epidemiology, mechanisms, etiologies, therapies, treatment guidelines, and future directions in the management of sudden cardiac death.
View details for DOI 10.1016/j.cpcardiol.2007.05.002
View details for Web of Science ID 000249579000002
View details for PubMedID 17723906
Impact of renal function on survival in patients with implantable cardioverter-defibrillators
PACE-PACING AND CLINICAL ELECTROPHYSIOLOGY
2007; 30 (3): 377-384
Although chronic renal insufficiency (CRI) is associated with increased cardiac and noncardiac mortality, there is limited data on the relationship between CRI and survival in patients with implantable cardioverter-defibrillators (ICDs), particularly across a wide range of renal function.We studied 507 consecutive patients receiving first-time ICDs from 1993-2003 at a single center. Preimplant serum creatinine measurements were used to determine glomerular filtration rate (GFR) and stage of chronic kidney disease (CKD). The primary outcome was time to death.During a mean follow-up of 4 years, all-cause mortality through completion of follow-up increased stepwise by GFR stage (I: 16%, II: 20%, III: 35%; IV: 40%; V: 50%; P < 0.001 for trend). After multivariate adjustment, CRI was independently associated with death (HR = 1.7, P = 0.02), as were a serum creatinine >or=2.0 mg/dL (HR 2.5, P = 0.003) and the presence of end-stage renal disease (HR 6.8; P < 0.001). For every 10-unit decrease in GFR, the adjusted hazard of death increased 12% (P = 0.04).The presence of CRI prior to implant is independently associated with increased mortality in patients receiving ICDs. The risk is proportional to the degree of renal dysfunction and is apparent even when GFR is only mildly reduced. Differences in mortality are observed within the first year of implant, and patients on dialysis are at highest risk. Because randomized trials of ICDs have not included large numbers of patients with moderate or severe renal disease, our findings may have important implications in prognosis and case selection of patients who otherwise meet current indications for ICD implantation.
View details for Web of Science ID 000244886500011
View details for PubMedID 17367357
Association of platelet count with residual thrombus in the myocardial infarct-related coronary artery among patients treated with fibrinolytic therapy for ST-segment elevation acute myocardial infarction
AMERICAN JOURNAL OF CARDIOLOGY
2004; 94 (11): 1406-1410
A higher platelet count is independently associated with the presence of residual thrombus in the infarct-related artery after administration of fibrinolytic therapy, even after multivariate adjustment.
View details for DOI 10.1016/j.amjcard.2004.08.015
View details for Web of Science ID 000225529600009
View details for PubMedID 15566912
Sequential risk stratification using TIMI risk score and TIMI flow grade among patients treated with fibrinolytic therapy for ST-segment elevation acute myocardial infarction
AMERICAN JOURNAL OF CARDIOLOGY
2004; 94 (9): 1113-1117
In the setting of ST-segment elevation myocardial infarction (STEMI), the Thrombolysis In Myocardial Infarction (TIMI) risk score (TRS) and indexes of epicardial and myocardial perfusion are associated with mortality. The association between TRS at presentation and angiographic indexes of epicardial and myocardial perfusion after reperfusion therapy has not been investigated. We hypothesized that TRS, TIMI flow grade (TFG), and TIMI myocardial perfusion grade (TMPG) would provide independent prognostic information and that angiographic indexes of poor flow and perfusion would be associated with a higher TRS. TRS and angiographic data were evaluated in 3,801 patients from the TIMI 4, 10A, 10B, 14, 20, 23, and 24 trials. Within each TRS stratum (TRS 0 to 2, 3 to 4, >/=5), 30-day mortality increased stepwise among patients with impaired TFG at 60 minutes after fibrinolytic administration. In a multivariate model adjusting for the TRS strata, impaired TMPG (0/1) was independently associated with higher mortality (odds ratio 2.28, p = 0.018). In a multivariate model adjusting for the TFG and infarct location, the likelihood of impaired TMPG (0/1) was greater among intermediate-risk (TRS 3 to 4) and high-risk (TRS >/=5) patients than among low-risk (TRS 0 to 2) patients (odds ratio 1.43, p = 0.019 and 1.50, p = 0.055, respectively). Thus, impaired epicardial flow and myocardial perfusion are independently associated with increased 30-day mortality among patients identified by TRS as high risk, although there is no synergism between either TFG or TMPG and TRS. High TRS at presentation is associated with abnormal myocardial perfusion, even after adjusting for possible confounders.
View details for DOI 10.1016/j.amjcard.2004.07.075
View details for Web of Science ID 000224837500002
View details for PubMedID 15518603
Association of the Fibonacci Cascade with the distribution of coronary artery lesions responsible for ST-segment elevation myocardial infarction
AMERICAN JOURNAL OF CARDIOLOGY
2003; 92 (5): 595-597
This is the first study to demonstrate the appearance of the Fibonacci Cascade within the distribution of coronary artery lesions in the human heart. The propensity for this ratio to appear in nature may also be because this ratio optimizes the efficiency of packing structures in a limited space in such a way that wasted space is minimized and the supply of energy or nutrients is optimized.
View details for DOI 10.1016/S0002-9149(03)00731-8
View details for Web of Science ID 000185060700020
View details for PubMedID 12943884
Meperidine and alfentanil do not reduce the gain or maximum intensity of shivering
1998; 88 (4): 858-865
Thermoregulatory shivering can be characterized by its threshold (triggering core temperature), gain (incremental intensity increase with further core temperature deviation), and maximum intensity. Meperidine (a combined mu- and kappa-agonist) treats shivering better than equianalgesic doses of pure mu-opioid agonists. Meperidine's special antishivering action is mediated, at least in part, by a disproportionate decrease in the shivering threshold. That is, meperidine decreases the shivering threshold twice as much as the vasoconstriction threshold, whereas alfentanil (a pure mu-agonist) decreases the vasoconstriction and shivering thresholds comparably. However, reductions in the gain or maximum shivering intensity might also contribute to the clinical efficacy of meperidine. Accordingly, we tested the hypothesis that meperidine reduces the gain and maximum intensity of shivering much more than alfentanil does.Ten volunteers were each studied on three separate days: (1) control (no drug); (2) a target total plasma meperidine concentration of 1.2 microg/ml; and (3) a target plasma alfentanil concentration of 0.2 microg/ml. Skin temperatures were maintained near 31 degrees C, and core temperatures were decreased by central-venous infusion of cold lactated Ringer's solution until maximum shivering intensity was observed. Shivering was evaluated using oxygen consumption and electromyography. A sustained increase in oxygen consumption identified the shivering threshold. The gain of shivering was calculated as the slope of the oxygen consumption versus core temperature regression, and as the slope of electromyographic intensity versus core temperature regression.Meperidine and alfentanil administration significantly decreased the shivering thresholds. However, neither meperidine nor alfentanil reduced the gain of shivering, as determined by either oxygen consumption or electromyography. Opioid administration also failed to significantly decrease the maximum intensity of shivering.The authors could not confirm the hypothesis that meperidine reduces the gain or maximum intensity of shivering more than alfentanil does. These results suggest that meperidine's special antishivering effect is primarily mediated by a disproportionate reduction in the shivering threshold.
View details for Web of Science ID 000073024700003
View details for PubMedID 9579492
Isoflurane alters shivering patterns and reduces maximum shivering intensity
1998; 88 (4): 866-873
Shivering can be characterized by its threshold (triggering core temperature), gain (incremental intensity increase with further core hypothermia), and maximum response intensity. Isoflurane produces a clonic muscular activity that is not a component of normal shivering. To the extent that clonic activity is superimposed on normal thermoregulatory shivering, the gain of shivering might be increased during isoflurane anesthesia. Conversely, volatile anesthetics decrease systemic oxygen consumption and peripherally inhibit skeletal muscle strength, which might limit maximum intensity despite central activation. The purpose of the present study was, therefore, to evaluate the effect of isoflurane shivering patterns and the gain and maximum intensity of shivering.Ten volunteers were each studied in two separate protocols: (1) control (no drug) and (2) 0.7% end-tidal isoflurane. On each day, the mean skin temperature was maintained at 31 degrees C. Core temperature was then reduced by infusion of cold fluid until shivering intensity no longer increased. The core temperature triggering the initial increase in oxygen consumption defined the shivering threshold. The gain of shivering was defined by the slope of the core temperature versus oxygen consumption regression. Pectoralis and quadriceps electromyography was used to evaluate anesthetic-induced facilitation of clonic (5-7 Hz) muscular activity.Isoflurane significantly decreased the shivering threshold from 36.4 +/- 0.3 to 34.2 +/- 0.8 degrees C. The increase in oxygen consumption was linear on the control day and was followed by sustained high-intensity activity. During isoflurane administration, shivering was characterized by bursts of intense shivering separated by quiescent periods. Isoflurane significantly increased the gain of shivering (as calculated from the initial increase), from -684 +/- 266 to -1483 +/- 752 ml x min(-1) x degrees C(-1). However, isoflurane significantly decreased the maximum intensity of shivering, from 706 +/- 144 to 489 +/- 80 ml/min. Relative electromyographic power in frequencies associated with clonus increased significantly when the volunteers were given isoflurane.These data indicate that isoflurane anesthesia markedly changes the overall pattern of shivering during progressive hypothermia from a linear increase to an unusual saw-tooth pattern. They further suggest that clonic muscular activity combines with shivering to increase the initial gain of shivering during isoflurane anesthesia, but that isoflurane peripherally inhibits the maximum expression of shivering.
View details for Web of Science ID 000073024700004
View details for PubMedID 9579493
Epidural anesthesia reduces and gain and maximum intensity of shivering
1998; 88 (4): 851-857
Shivering can be characterized by its threshold (triggering core temperature), gain (incremental intensity increase), and maximum intensity. The gain of shivering might be preserved during epidural or spinal anesthesia if control mechanisms compensate for lower-body paralysis by augmenting the activity of upper-body muscles. Conversely, gain will be reduced approximately by half if the thermoregulatory system fails to compensate. Similarly, appropriate regulatory feedback might maintain maximum shivering intensity during regional anesthesia. Accordingly, the gain and maximum intensity of shivering during epidural anesthesia were determined.Seven volunteers participated on two randomly ordered study days. On one day (control), no anesthesia was administered; on the other, epidural anesthesia was maintained at a T8 sensory level. Shivering, at a mean skin temperature near 33 degrees C, was provoked by central-venous infusion of cold fluid; core cooling continued until shivering intensity no longer increased. Shivering was evaluated by systemic oxygen consumption and electromyography of two upper-body and two lower-body muscles. The core temperature triggering an increase in oxygen consumption identified the shivering threshold. The slopes of the oxygen consumption versus core temperature and electromyographic intensity versus core temperature regressions identified systemic and regional shivering gains, respectively.The shivering threshold was reduced by epidural anesthesia by approximately 0.4 degrees C, from 36.7 +/- 0.6 to 36.3 +/- 0.5 degrees C (means +/- SD; P < 0.05). Systemic gain, as determined by oxygen consumption, was reduced from -581 +/- 186 to -215 +/- 154 ml x min(-1) x degrees C(-1) (P < 0.01). Lower-body gain, as determined electromyographically, was essentially obliterated by paralysis during epidural anesthesia, decreasing from -0.73 +/- 0.85 to -0.04 +/- 0.06 intensity units/degrees C (P < 0.01). However, upper-body gain had no compensatory increase: -1.3 +/- 1.1 units/degrees C control versus 2.0 +/- 2.1 units/degrees C epidural. Maximum oxygen consumption was decreased by one third during epidural anesthesia: 607 +/- 82 versus 412 +/- 50 ml/min (P < 0.05).These results confirm that regional anesthesia reduces the shivering threshold. Epidural anesthesia reduced the gain of shivering by 63% because upper-body muscles failed to compensate for lower-body paralysis. The thermoregulatory system thus fails to recognize that regional anesthesia reduces metabolic heat production, instead responding as if lower-body muscular activity remained intact.
View details for Web of Science ID 000073024700002
View details for PubMedID 9579491
Postanesthetic vasoconstriction slows peripheral-to-core transfer of cutaneous heat, thereby isolating the core thermal compartment
ANESTHESIA AND ANALGESIA
1997; 85 (4): 899-906
Forced-air warming during anesthesia increases core temperature comparably with and without thermoregulatory vasoconstriction. In contrast, postoperative forced-air warming may be no more effective than passive insulation. Nonthermoregulatory anesthesia-induced vasodilation may thus influence heat transfer. We compared postanesthetic core rewarming rates in volunteers given cotton blankets or forced air. Additionally, we compared increases in peripheral and core heat contents in the postanesthetic period with data previously acquired during anesthesia to determine how much vasomotion alters intercompartmental heat transfer. Six men were anesthetized and cooled passively until their core temperatures reached 34 degrees C. Anesthesia was then discontinued, and shivering was prevented by giving meperidine. On one day, the volunteers were covered with warmed blankets for 2 h; on the other, volunteers were warmed with forced air. Peripheral tissue heat contents were determined from intramuscular and skin thermocouples. Predicted changes in core temperature were calculated assuming that increases in body heat content were evenly distributed. Predicted changes were thus those that would be expected if vasomotor activity did not impair peripheral-to-core transfer of applied heat. These results were compared with those obtained previously in a similar study of anesthetized volunteers. Body heat content increased 159 +/- 35 kcal (mean +/- SD) more during forced-air than during blanket warming (P < 0.001). Both peripheral and core temperatures increased significantly faster during active warming: 3.3 +/- 0.7 degrees C and 1.1 +/- 0.4 degrees C, respectively. Nonetheless, predicted core temperature increase during forced-air warming exceeded the actual temperature increase by 0.8 +/- 0.3 degree C (P < 0.001). Vasoconstriction thus isolated core tissues from heat applied to the periphery, with the result that core heat content increased 32 +/- 12 kcal less than expected after 2 h of forced-air warming (P < 0.001). In contrast, predicted and actual core temperatures differed only slightly in the anesthetized volunteers previously studied. In contrast to four previous studies, our results indicate that forced-air warming increases core temperature faster than warm blankets. Postanesthetic vasoconstriction nonetheless impeded peripheral-to-core heat transfer, with the result that core temperatures in the two groups differed less than might be expected based on systemic heat balance estimates. Implications: Comparing intercompartmental heat flow in our previous and current studies suggests that anesthetic-induced vasodilation influences intercompartmental heat transfer and distribution of body heat more than thermoregulatory shunt vasomotion.
View details for Web of Science ID A1997XY23200034
View details for PubMedID 9322477
Rapid core-to-peripheral tissue heat transfer during cutaneous cooling
ANESTHESIA AND ANALGESIA
1996; 82 (5): 925-930
Perioperative thermal manipulations are usually directed at the skin surface because methods of directly warming the core are invasive or ineffective. However, inadequate heat flow between peripheral and core compartments will decrease the rate at which core temperature changes. We therefore determined whether core hypothermia is delayed after initiation of surface cooling. Six volunteers were anesthetized with propofol and midazolam, and maintained under three layers of passive insulation for 2.5-4 h. Subsequently, the skin surface was cooled using forced air, 1000 L/min, at 10 degrees C. Isoflurane was added as necessary to maintain arteriovenous shunt vasodilation. Overall heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. Overall body heat content decreased approximately 234 kcal during 2.5 h of active cooling. Core temperature, which was nearly constant before active cooling, decreased approximately 1.3 degrees C/h. There was no delay between initiation of active cooling and the decrease in core temperature. Furthermore, peripheral (arm and leg) and core (trunk and head) tissue heat contents decreased at virtually the same rates: approximately 50 kcal/h and approximately 47 kcal/h, respectively. These data indicate that there is little restriction of heat flow between peripheral and core tissues in vasodilated, anesthetized subjects.
View details for Web of Science ID A1996UH19500006
View details for PubMedID 8610900