
Byron Lee
Professor of Medicine (Cardiovascular)
Medicine - Cardiovascular Medicine
Clinical Focus
- Clinical Cardiac Electrophysiology
- Cardiology
Professional Education
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Masters, University of California, San Francisco, Clinical Research (2006)
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Board Certification: American Board of Internal Medicine, Clinical Cardiac Electrophysiology (2003)
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Fellowship: Stanford University Clinical Cardiac Electrophysiology Fellowship (2001) CA
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Board Certification: American Board of Internal Medicine, Cardiovascular Disease (2001)
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Fellowship: Stanford University Cardiovascular Medicine Fellowship Program (2000) CA
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Residency: Stanford University Internal Medicine Residency (1997) CA
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Medical Education: Harvard Medical School (1994) MA
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Undergraduate, University of California, Berkeley, Social Welfare (1989)
All Publications
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A Tale of 2 Troubling Tachycardias.
JACC. Clinical electrophysiology
2024
View details for DOI 10.1016/j.jacep.2024.09.002
View details for PubMedID 39480390
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Acute alcohol exposure and electrocardiographic changes: Finding from the HOLIDAY trial
JOURNAL OF ELECTROCARDIOLOGY
2024; 83: 26-29
View details for DOI 10.1016/j.jelectrocard.2024.01.003
View details for Web of Science ID 001175991000001
View details for PubMedID 38295539
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Palpitations and Recurrent Syncope in a Young Woman
CIRCULATION
2024; 149 (5): 402-405
View details for DOI 10.1161/CIRCULATIONAHA.123.067865
View details for Web of Science ID 001150598700006
View details for PubMedID 38285741
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Comparison of non-laser and laser transvenous lead extraction: a systematic review and meta-analysis
EUROPACE
2023; 25 (11)
Abstract
Transvenous lead extraction (TLE) is performed using non-laser and laser techniques with overall high efficacy and safety. Variation in outcomes between the two approaches does exist with limited comparative evidence in the literature. We sought to compare non-laser and laser TLE in a meta-analysis.We searched Medline, Embase, Scopus, ClinicalTrials.gov, and CENTRAL databases for TLE studies published between 1991 and 2021. From the included 68 studies, safety and efficacy data were carefully evaluated and extracted. Aggregated cases of outcomes were used to calculate odds ratio (OR), and pooled rates were synthesized from eligible studies to compare non-laser and laser techniques. Subgroup comparison of rotational tool and laser extraction was also performed. Non-laser in comparison with laser had lower procedural mortality (pooled rate 0% vs. 0.1%, P < 0.01), major complications (pooled rate 0.7% vs. 1.7%, P < 0.01), and superior vena cava (SVC) injury (pooled rate 0% vs. 0.5%, P < 0.001), with higher complete success (pooled rate 96.5% vs. 93.8%, P < 0.01). Non-laser comparatively to laser was more likely to achieve clinical [OR 2.16 (1.77-2.63), P < 0.01] and complete [OR 1.87 (1.69-2.08), P < 0.01] success, with a lower procedural mortality risk [OR 1.6 (1.02-2.5), P < 0.05]. In the subgroup analysis, rotational tool compared with laser achieved greater complete success (pooled rate 97.4% vs. 95%, P < 0.01) with lower SVC injury (pooled rate 0% vs. 0.7%, P < 0.01).Non-laser TLE is associated with a better safety and efficacy profile when compared with laser methods. There is a greater risk of SVC injury associated with laser sheath extraction.
View details for DOI 10.1093/europace/euad316
View details for Web of Science ID 001102685200006
View details for PubMedID 37882609
View details for PubMedCentralID PMC10638006
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A Randomized Trial of High vs Standard Power Radiofrequency Ablation for Pulmonary Vein Isolation SHORT-AF
JACC-CLINICAL ELECTROPHYSIOLOGY
2023; 9 (7): 1038-1047
Abstract
High-power, short duration (HPSD) radiofrequency ablation (RFA) is a commonly used strategy for pulmonary vein isolation (PVI).This study sought to compare HPSD with standard power, standard duration (SPSD) RFA in patients undergoing PVI.Patients with paroxysmal or persistent (<1 year) atrial fibrillation (AF) were randomized to HPSD (50 W) or SPSD (25-30 W) RFA to achieve PVI. Outcomes assessed included time to achieve PVI (primary), left atrial dwell time, total procedure time, first-pass isolation, PV reconnection with adenosine, procedure complications including asymptomatic cerebral emboli (ACE), and freedom from atrial arrhythmias.Sixty patients (median age 66 years; 75% male) with paroxysmal (57%) or persistent (43%) AF were randomized to HPSD (n = 29) or SPSD (n = 31). Median time to achieve PVI was shorter with HPSD vs SPSD (87 minutes vs 126 minutes; P = 0.003), as was left atrial dwell time (157 minutes vs 180 minutes; P = 0.04). There were no differences in first-pass isolation (79% vs 76%; P = 0.65) or PV reconnection with adenosine (12% vs 20%; P = 0.26) between groups. At 12 months, recurrent atrial arrhythmias occurred less in the HPSD group compared with the SPSD group (n = 3 of 29 [10%] vs n = 11 of 31 [35%]; HR: 0.26; P = 0.027). There was a trend toward more ACE with HPSD RFA (40% HPSD vs 17% SPSD; P = 0.053).In patients undergoing AF ablation, HPSD compared with SPSD RFA results in shorter time to achieve PVI, greater freedom from AF at 12 months, and a trend toward increased ACE.
View details for DOI 10.1016/j.jacep.2022.12.020
View details for Web of Science ID 001059867100001
View details for PubMedID 37495318
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Randomized Comparison of a Radiofrequency Wire Versus a Radiofrequency Needle System for Transseptal Puncture
JACC-CLINICAL ELECTROPHYSIOLOGY
2023; 9 (5): 611-619
Abstract
Transseptal puncture is a necessary component of many electrophysiology and structural heart procedures. Improving this technique has broad ramifications for the overall efficiency and safety of these interventions. A new technology uses a specialized introducer wire to cross the septum with radiofrequency (RF) energy, eliminating the need for a transseptal needle and wire/needle exchanges.This study sought to compare the efficacy and safety of an RF needle versus RF wire approach for transseptal puncture.Individuals ≥18 years of age undergoing double transseptal puncture for atrial fibrillation or left atrial flutter ablation were randomized to a transseptal approach with either an RF needle or RF wire. The primary outcome was time to achieve first transseptal puncture. Secondary outcomes included second and combined transseptal puncture time, fluoroscopy time, number of equipment exchanges, and complications.A total of 75 participants were enrolled (36 RF needle, 39 RF wire). No crossovers occurred. Randomization to the RF wire resulted in a significant reduction in first transseptal time compared with the RF needle (median 9.2 [IQR: 5.7-11.2] minutes vs 6.9 [IQR: 5.2-8.4] minutes, P = 0.03). Second and combined transseptal times, and number of equipment exchanges, were also reduced with the RF wire. One participant in the RF needle group experienced transient atrioventricular block due to mechanical trauma from the sheath/dilator assembly. There were no complications in the RF wire group.The RF wire technique resulted in faster time to transseptal puncture and fewer equipment exchanges compared with an RF needle with no difference in complications.
View details for DOI 10.1016/j.jacep.2022.10.017
View details for Web of Science ID 001055363700001
View details for PubMedID 36752451
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The Value of Programmed Ventricular Extrastimuli From the Right Ventricular Basal Septum During Supraventricular Tachycardia.
JACC. Clinical electrophysiology
2023; 9 (2): 219-228
Abstract
The difference between the right ventricular (RV) apical stimulus-atrial electrogram (SA) interval during resetting of supraventricular tachycardia (SVT) versus the ventriculoatrial (VA) interval during SVT (ΔSA-VAapex) is an established technique for discerning SVT mechanisms but is limited by a significant diagnostic overlap.This study hypothesized that the difference between the RV SA interval during resetting of SVTs versus the VA interval during SVTs (ΔSA-VA) would yield a more robust differentiation of atrioventricular nodal re-entrant tachycardia (AVNRT) from atrioventricular reciprocating tachycardia (AVRT) when using the RV basal septal stimulation (ΔSA-VAbase) as compared to the RV apical stimulation (ΔSA-VAapex). Moreover, it was predicted that the ΔSA-VAbase might distinguish septal from free wall accessory pathways (APs) effectively.In this prospective study, 105 patients with AVNRTs (age 48 ± 20 years, 44% male) and 130 with AVRTs (age 26 ± 18 years, 54% male) underwent programmed ventricular extrastimuli delivered from both the RV basal septum and RV apex. The ΔSA-VA values were compared between the 2 sites.The ΔSA-VAbase was shorter than the ΔSA-VAapex during AVRT (44 ± 30 ms vs 58 ± 29 ms; P < 0.001), and the opposite occurred during AVNRT (133 ± 31 ms vs 125 ± 25 ms; P = 0.03). A ΔSA-VAbase of ≧85 milliseconds had a sensitivity of 97% and specificity of 96% for identifying AVNRT. Furthermore, a ΔSA-VAbase of 45-85 milliseconds identified AVRT with left free wall APs (sensitivity 86%, specificity 95%), 20-45 milliseconds for posterior septal APs (sensitivity 72%, specificity 96%), and <20 milliseconds for right free wall or anterior/mid septal APs (sensitivity 86%, specificity 98%).The ΔSA-VAbase during programmed ventricular extrastimuli produced a robust differentiation between AVNRT and AVRT regardless of the AP location with ≧85 milliseconds as an excellent cutoff point. This straightforward technique further allowed localizing 4 general AP sites.
View details for DOI 10.1016/j.jacep.2022.09.005
View details for PubMedID 36858688
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Risk Factors for Arrhythmic Death, Overall Mortality, and Ventricular Tachyarrhythmias Requiring Shock After Myocardial Infarction
AMERICAN JOURNAL OF CARDIOLOGY
2023; 187: 9
Abstract
The VEST (Vest Prevention of Early Sudden Death Trial) showed a trend toward decreased sudden death and lower overall mortality with a wearable cardioverter-defibrillator (WCD) in the postmyocardial infarction (post-MI) period. However, it is unclear which patients should receive WCD therapy. We aimed to identify the risk factors for arrhythmic death, all-cause mortality, and ventricular tachyarrhythmias requiring appropriate shock to identify patients most likely to benefit from a WCD. The VEST trial included patients with acute MI with ejection fraction ≤35%. Using logistic regression, 7 risk factors were evaluated for association with arrhythmic death, all-cause mortality, and appropriate shock. Among 2,302 participants, 44 had arrhythmic death (1.9%) and 86 died of any cause (3.7%). Among 1,524 participants randomized to WCD, 20 experienced appropriate shock (1.3%) over 90 days. In the multivariable analyses, lower systolic blood pressure (SBP; odds ratio [OR] 1.64 per 10 mm Hg) and higher heart rate at discharge (OR 1.19 per 10 beats/min) were associated with arrhythmic death. Lower SBP (OR 1.37) and higher heart rate (OR 1.10) were associated with all-cause mortality. Higher heart rate (OR 1.20) was associated with appropriate shock. Patients with both SBP ≤100 and heart rate ≥100 were at increased odds of arrhythmic death (OR 4.82), all-cause mortality (OR 3.10), and appropriate shock (OR 6.13). In patients with acute MI and reduced ejection fraction, lower SBP and higher heart rate at discharge were strongly associated with arrhythmic death and all-cause mortality. In conclusion, these risk factors identify a select group at high risk of adverse events in a setting where WCD therapy is reasonable.
View details for DOI 10.1016/j.amjcard.2022.10.009
View details for Web of Science ID 000916876200005
View details for PubMedID 36459743
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From Improving Survival to Cost Savings for the Health SystemdRemote Monitoring for All?
CANADIAN JOURNAL OF CARDIOLOGY
2022; 38 (6): 712-714
View details for DOI 10.1016/j.cjca.2022.01.032
View details for Web of Science ID 000841434200004
View details for PubMedID 35150823
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A peculiar case of palpitations and syncope
HEART RHYTHM
2022; 19 (3): 505-507
View details for DOI 10.1016/j.hrthm.2021.11.019
View details for Web of Science ID 000784332300029
View details for PubMedID 35227417
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Acute Consumption of Alcohol and Discrete Atrial Fibrillation Events
ANNALS OF INTERNAL MEDICINE
2021; 174 (11): 1503-+
Abstract
Patients' self-reports suggest that acute alcohol consumption may trigger a discrete atrial fibrillation (AF) event.To objectively ascertain whether alcohol consumption heightens risk for an AF episode.A prospective, case-crossover analysis.Ambulatory persons in their natural environments.Consenting patients with paroxysmal AF.Participants were fitted with a continuous electrocardiogram (ECG) monitor and an ankle-worn transdermal ethanol sensor for 4 weeks. Real-time documentation of each alcoholic drink consumed was self-recorded using a button on the ECG recording device. Fingerstick blood tests for phosphatidylethanol (PEth) were used to corroborate ascertainments of drinking events.Of 100 participants (mean age, 64 years [SD, 15]; 79% male; 85% White), 56 had at least 1 episode of AF. Results of PEth testing correlated with the number of real-time recorded drinks and with events detected by the transdermal alcohol sensor. An AF episode was associated with 2-fold higher odds of 1 alcoholic drink (odds ratio [OR], 2.02 [95% CI, 1.38 to 3.17]) and greater than 3-fold higher odds of at least 2 drinks (OR, 3.58 [CI, 1.63 to 7.89]) in the preceding 4 hours. Episodes of AF were also associated with higher odds of peak blood alcohol concentration (OR, 1.38 [CI, 1.04 to 1.83] per 0.1% increase in blood alcohol concentration) and the total area under the curve of alcohol exposure (OR, 1.14 [CI, 1.06 to 1.22] per 4.7% increase in alcohol exposure) inferred from the transdermal ethanol sensor in the preceding 12 hours.Confounding by other time-varying exposures that may accompany alcohol consumption cannot be excluded, and the findings from the current study of patients with AF consuming alcohol may not apply to the general population.Individual AF episodes were associated with higher odds of recent alcohol consumption, providing objective evidence that a modifiable behavior may influence the probability that a discrete AF event will occur.National Institute on Alcohol Abuse and Alcoholism.
View details for DOI 10.7326/M21-0228
View details for Web of Science ID 000743694300015
View details for PubMedID 34461028
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Incessant multiform ectopy in a young woman: What is the mechanism and treatment?
HEART RHYTHM
2021; 18 (9): 1615-1616
View details for DOI 10.1016/j.hrthm.2021.05.027
View details for Web of Science ID 000700405300021
View details for PubMedID 34474745
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Wearable cardioverter-defibrillators: A review of evidence and indications * , **
TRENDS IN CARDIOVASCULAR MEDICINE
2021; 31 (3): 196-201
Abstract
The wearable cardioverter-defibrillator (WCD) was first approved for clinical use in 2002, and is routinely used in select populations at high risk for sudden cardiac death. WCDs are frequently considered as a bridge to definitive therapy or in circumstances where insertion of conventional implantable cardioverter-defibrillators (ICD) is temporarily contraindicated. In this review, we summarize the literature on WCDs. From prospective trials to the first randomized controlled trial with WCD, there is a growing body of evidence that suggests that the WCD is safe and effective. In the first randomized controlled trial of the WCD (VEST Trial), there was no reduction in arrhythmia death but there was a reduction in all-cause mortality. We discuss the mortality impact, rate of inappropriate shocks, compliance, and potential quality of life implications with the WCD. Finally, we present the evidence for WCD use in select populations (e.g., post-myocardial infarction, device extraction), and the current guideline recommendations for WCD use.
View details for DOI 10.1016/j.tcm.2020.03.002
View details for Web of Science ID 000631796700011
View details for PubMedID 32205034
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A Randomized, Double-Blind, Placebo-Controlled Trial of Intravenous Alcohol to Assess Changes in Atrial Electrophysiology.
JACC. Clinical electrophysiology
2021
Abstract
This study sought to identify acute changes in human atrial electrophysiology during alcohol exposure.The mechanism by which a discrete episode of atrial fibrillation (AF) occurs remains unknown. Alcohol appears to increase the risk for AF, providing an opportunity to study electrophysiologic effects that may render the heart prone to arrhythmia.In this randomized, double-blinded, placebo-controlled trial, intravenous alcohol titrated to 0.08% blood alcohol concentration was compared with a volume and osmolarity-matched, masked, placebo in patients undergoing AF ablation procedures. Right, left, and pulmonary vein atrial effective refractory periods (AERPs) and conduction times were measured pre- and post-infusion. Isoproterenol infusions and burst atrial pacing were used to assess AF inducibility.Of 100 participants (50 in each group), placebo recipients were more likely to be diabetic (22% vs 4%; p = 0.007) and to have undergone a prior AF ablation (36% vs. 22%; p = 0.005). Pulmonary vein AERPs decreased an average of 12 ms (95% confidence interval: 1 to 22 ms; p = 0.026) in the alcohol group, with no change in the placebo group (p = 0.98). Whereas no statistically significant differences in continuously assessed AERPs were observed, the proportion of AERP sites tested that decreased with alcohol (median: 0.5; interquartile range: 0.6, 0.6) was larger than with placebo (median: 0.4; interquartile range: 0.2, 0.6; p = 0.0043). No statistically significant differences in conduction times or in the proportion with inducible AF were observed.Acute exposure to alcohol reduces AERP, particularly in the pulmonary veins. These data demonstrate a direct mechanistic link between alcohol, a common lifestyle exposure, and immediate proarrhythmic effects in human atria. (How Alcohol Induces Atrial Tachyarrhythmias Study [HOLIDAY]; NCT01996943).
View details for DOI 10.1016/j.jacep.2020.11.026
View details for PubMedID 33516710
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Predictors of adverse outcome in patients with frequent premature ventricular complexes: The ABC-VT risk score
HEART RHYTHM
2020; 17 (7): 1066-1074
Abstract
No independently validated score currently exists for risk stratification of patients with frequent premature ventricular complexes (PVCs).The purpose of this study was to develop a risk score to predict adverse events in patients with frequent PVCs.We analyzed consecutive patients between 2012 and 2017 undergoing 14-day continuous monitoring with frequent PVCs (>5%) and concurrent echocardiography. We performed binary logistic regression to determine multivariate predictors of adverse left ventricular remodeling (left ventricular ejection fraction [LVEF] <45% or left ventricular end-diastolic volume index >75 mL/m2). A risk score was created using the log(odds ratio (OR)) of these predictors and validated prospectively to determine the risk of future adverse events in those with baseline LVEF >45%. An adverse event was defined as LVEF decline by 10%, heart failure hospitalization, or cardiovascular mortality. Two validation cohorts were used: follow-up from the original derivation cohort (cohort 1) and an independent Korean PVC registry (cohort 2).The derivation cohort comprised 206 patients with a mean PVC burden of 11.6% ± 6.2% and considerable daily fluctuation (minimum burden 7.3% ± 6.2% vs maximum 17.9% ± 8.0%). Independent predictors of adverse remodeling were as follows: superiorly directed PVC axis (OR 2.7; 1 point), PVC burden 10%-20% (OR 3.5; 2 points) and >20% (OR 4.4; 3 points), PVC coupling interval >500 ms (OR 4.7; 4 points), nonsustained ventricular tachycardia (OR 5.3; 4 points), which form the ABC-VT risk score. This score predicted future adverse events in both validation cohorts: cohort 1, hazard ratio 1.43; 95% confidence interval 1.19-1.73; P < .001 and cohort 2, hazard ratio 1.22; 95% confidence interval 1.05-1.42; P = .01.The ABC-VT score is a simple tool that predicts adverse left ventricular remodeling and future clinical deterioration in patients with frequent PVCs.
View details for DOI 10.1016/j.hrthm.2020.02.020
View details for Web of Science ID 000544861000003
View details for PubMedID 32109563
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Mortality during transvenous lead extraction: is there a difference between laser sheaths and rotating sheaths?-Authors' reply
EUROPACE
2020; 22 (6): 989-990
View details for DOI 10.1093/europace/euaa054
View details for Web of Science ID 000542050300026
View details for PubMedID 32274509
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INTERACTION OF WIRELESS HEADPHONES, SMARTWATCHES, AND WIFI ROUTERS WITH ICDS
ELSEVIER SCIENCE INC. 2020: 499
View details for Web of Science ID 000522979100488
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Variable Presentations and Ablation Sites for Manifest Nodoventricular/Nodofascicular Fibers.
Circulation. Arrhythmia and electrophysiology
2019; 12 (9): e007337
Abstract
BACKGROUND: Nodofascicular and nodoventricular (NFV) accessory pathways connect the atrioventricular node and the Purkinje system or ventricular myocardium, respectively. Concealed NFV pathways participate as the retrograde limb of supraventricular tachycardia (SVT). Manifest NFV pathways can comprise the anterograde limb of wide-complex SVT but are quite rare. The purpose of this report is to highlight the electrophysiological properties and sites of ablation for manifest NFV pathways.METHODS: Eight patients underwent electrophysiology studies for wide-complex tachycardia (3), for narrow-complex tachycardia (1), and preexcitation (4).RESULTS: NFV was an integral part of the SVT circuit in 3 patients. Cases 1 to 2 were wide-complex tachycardia because of manifest NFV SVT. Case 3 was a bidirectional NFV that conducted retrograde during concealed NFV SVT and anterograde causing preexcitation during atrial pacing. NFV was a bystander during atrioventricular node re-entrant tachycardia, atrial fibrillation, atrial flutter, and orthodromic atrioventricular re-entrant tachycardia in 4 cases and caused only preexcitation in 1. Successful NFV ablation was achieved empirically in the slow pathway region in 1 case. In 5 cases, the ventricular insertion was mapped to the slow pathway region (2 cases) or septal right ventricle (3 cases). The NFV was not mapped in cases 5 and 7 because of its bystander role. QRS morphology of preexcitation predicted the right ventricle insertion sites in 4 of the 5 cases in which it was mapped. During follow-up, 1 patient noted recurrent palpitations but no documented SVT.CONCLUSIONS: Manifest NFV may be critical for wide-complex tachycardia/manifest NFV SVT, act as the retrograde limb for narrow-complex tachycardia/concealed NFV SVT, or cause bystander preexcitation. Ablation should initially target the slow pathway region, with mapping of the right ventricle insertion site if slow pathway ablation is not successful. The QRS morphology of maximal preexcitation may be helpful in predicting successful right ventricle ablation site.
View details for DOI 10.1161/CIRCEP.119.007337
View details for PubMedID 31505948
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The wearable cardioverter-defibrillator vest: Indications and ongoing questions
PROGRESS IN CARDIOVASCULAR DISEASES
2019; 62 (3): 256-264
Abstract
Multiple clinical trials have demonstrated the efficacy of implantable cardioverter-defibrillators (ICDs) for the prevention of sudden cardiac death (SCD) among specific high-risk populations. However, it remains unclear how to optimally treat those patients who are at elevated risk of cardiac arrest but are not among the presently identified groups proven to benefit from an ICD, are unable to tolerate surgical device implantation, or refuse invasive therapies. The wearable cardioverter-defibrillator (WCD) is an alternative antiarrhythmic device that provides continuous cardiac monitoring and defibrillation capabilities through a noninvasive, electrode-based system. The WCD has been shown to be highly effective at restoration of sinus rhythm in patients with a ventricular tachyarrhythmia, and one randomized trial using the WCD in patients with recent myocardial infarction at elevated risk for arrhythmic death reported a decrease in overall mortality despite no SCD mortality benefit. The current clinical indications for WCD use are varied and continue to evolve as experience with this technology increases.
View details for DOI 10.1016/j.pcad.2019.05.005
View details for Web of Science ID 000474940300009
View details for PubMedID 31077726
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Wearable Cardioverter-Defibrillator after Myocardial Infarction REPLY
NEW ENGLAND JOURNAL OF MEDICINE
2019; 380 (6): 600-601
View details for Web of Science ID 000457854200019
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Wearable Cardioverter-Defibrillator after Myocardial Infarction.
The New England journal of medicine
2019; 380 (6): 600-601
View details for DOI 10.1056/NEJMc1816889
View details for PubMedID 30726697
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Surface ECG and intracardiac spectral measures predict atrial fibrillation recurrence after catheter ablation.
Journal of cardiovascular electrophysiology
2018; 29 (10): 1371-1378
Abstract
Outcome of patients undergoing catheter ablation of atrial fibrillation (AF) varies widely. We sought to investigate whether parameters derived from the spectral analysis of surface ECG and intracardiac AF electrograms can predict outcome in patients referred for pulmonary vein isolation (PVI).We performed spectral analysis on the surface ECG and intracardiac electrograms from patients referred for AF ablation. After filtering and QRST subtraction, we measured the dominant frequency (DF), regularity index (RI) and the organizational index (OI) of fibrillatory electrograms and determined their value for predicting AF recurrence after ablation. A subjective, blinded prediction based on the surface ECG was also performed.We analyzed data from 153 PVI procedures in 140 patients (67.1% with persistent or longstanding AF). In a multivariable model, DF in the right atrium (RA) and distal coronary sinus (CSd)-to-RA DF gradient predicted AF recurrence (OR, 3.52, P = 0.023 and OR, 0.2, P = 0.034, respectively). DF in RA and CSd to RA DF gradient had a good predictive value for PVI outcome (area under the curve [AUC] of 0.73, P = 0.007 and 0.74, P = 0.007, respectively). These performed better than the subjective predictions of experienced electrophysiologists ( P = 0.2).Higher RA DF, lower CSd to RA DF gradient predicted recurrence after AF ablation. These spectral measures suggest a more remodeled atrial substrate and may provide simple tools for risk stratification or predict the need for additional substrate modification in patients referred for AF ablation.
View details for DOI 10.1111/jce.13699
View details for PubMedID 30016007
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Wearable Cardioverter-Defibrillator after Myocardial Infarction
NEW ENGLAND JOURNAL OF MEDICINE
2018; 379 (13): 1205–15
Abstract
Despite the high rate of sudden death after myocardial infarction among patients with a low ejection fraction, implantable cardioverter-defibrillators are contraindicated until 40 to 90 days after myocardial infarction. Whether a wearable cardioverter-defibrillator would reduce the incidence of sudden death during this high-risk period is unclear.We randomly assigned (in a 2:1 ratio) patients with acute myocardial infarction and an ejection fraction of 35% or less to receive a wearable cardioverter-defibrillator plus guideline-directed therapy (the device group) or to receive only guideline-directed therapy (the control group). The primary outcome was the composite of sudden death or death from ventricular tachyarrhythmia at 90 days (arrhythmic death). Secondary outcomes included death from any cause and nonarrhythmic death.Of 2302 participants, 1524 were randomly assigned to the device group and 778 to the control group. Participants in the device group wore the device for a median of 18.0 hours per day (interquartile range, 3.8 to 22.7). Arrhythmic death occurred in 1.6% of the participants in the device group and in 2.4% of those in the control group (relative risk, 0.67; 95% confidence interval [CI], 0.37 to 1.21; P=0.18). Death from any cause occurred in 3.1% of the participants in the device group and in 4.9% of those in the control group (relative risk, 0.64; 95% CI, 0.43 to 0.98; uncorrected P=0.04), and nonarrhythmic death in 1.4% and 2.2%, respectively (relative risk, 0.63; 95% CI, 0.33 to 1.19; uncorrected P=0.15). Of the 48 participants in the device group who died, 12 were wearing the device at the time of death. A total of 20 participants in the device group (1.3%) received an appropriate shock, and 9 (0.6%) received an inappropriate shock.Among patients with a recent myocardial infarction and an ejection fraction of 35% or less, the wearable cardioverter-defibrillator did not lead to a significantly lower rate of the primary outcome of arrhythmic death than control. (Funded by the National Institutes of Health and Zoll Medical; VEST ClinicalTrials.gov number, NCT01446965 .).
View details for DOI 10.1056/NEJMoa1800781
View details for Web of Science ID 000445835100005
View details for PubMedID 30280654
View details for PubMedCentralID PMC6276371
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Effect of a single dose of i.v. ondansetron on QTc interval in emergency department patients
AMERICAN JOURNAL OF HEALTH-SYSTEM PHARMACY
2018; 75 (5): 276-282
Abstract
Results of a study to determine whether i.v. administration of a single dose of 4 mg of ondansetron was associated with QT interval prolongation in emergency department (ED) patients are reported.In a prospective observational study conducted at an urban academic medical center ED, a convenience sample of adult ED patients treated with ondansetron 4 mg i.v. were enrolled. A 12-lead electrocardiogram (ECG) was obtained immediately before and 5 minutes after ondansetron administration. Measurements of heart rate-corrected QT interval (QTc measurements) provided by ECG machines were evaluated. An electrophysiologist analyzed all ECGs for adverse electrical events and verified the accuracy of QTc values. The primary objective was to measure the QTc change from baseline after ondansetron administration. The secondary objective was to describe adverse electrical cardiac events. Interactions between ondansetron and patients' home medications or ED-provided medications were analyzed.Among patients included in the data analysis (n = 20), ondansetron administration was associated with a mean QTc increase of 16.2 msec (95% confidence interval, 4.2-28.2 msec; p = 0.01) and a median increase of 12 msec (interquartile range, 5.5-18.0 msec; p < 0.01). One patient had a significant cardiac event (pulseless electrical activity) that was likely unrelated to ondansetron use. The home medications of 9 patients (42.9%) were deemed to pose a risk of torsades de pointes, and 17 major QT-prolonging drug-drug interactions were identified.Significant QTc prolongation occurred in ED patients receiving a single 4-mg i.v. dose of ondansetron. None of the patients had an ondansetron-related cardiac adverse event.
View details for DOI 10.2146/ajhp161070
View details for Web of Science ID 000425958800006
View details for PubMedID 29317399
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For cryoballoon ablation, time to effect is time well spent
HEART RHYTHM
2017; 14 (9): 1326-1327
View details for DOI 10.1016/j.hrthm.2017.07.016
View details for Web of Science ID 000408584300013
View details for PubMedID 28713025
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Primary Prevention of Sudden Cardiac Death Early Post-Myocardial Infarction Root Cause Analysis for Implantable Cardioverter-Defibrillator Failure and Currently Available Options
CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY
2017; 10 (6)
View details for DOI 10.1161/CIRCEP.117.005194
View details for Web of Science ID 000403880200011
View details for PubMedID 28630173
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Brain Emboli After Left Ventricular Endocardial Ablation
CIRCULATION
2017; 135 (9): 867-877
Abstract
Catheter ablation for ventricular tachycardia and premature ventricular complexes (PVCs) is common. Catheter ablation of atrial fibrillation is associated with a risk of cerebral emboli attributed to cardioversions and numerous ablation lesions in the low-flow left atrium, but cerebral embolic risk in ventricular ablation has not been evaluated.We enrolled 18 consecutive patients meeting study criteria scheduled for ventricular tachycardia or PVC ablation over a 9-month period. Patients undergoing left ventricular (LV) ablation were compared with a control group of those undergoing right ventricular ablation only. Patients were excluded if they had implantable cardioverter defibrillators or permanent pacemakers. Radiofrequency energy was used for ablation in all cases and heparin was administered with goal-activated clotting times of 300 to 400 seconds for all LV procedures. Pre- and postprocedural brain MRI was performed on each patient within a week of the ablation procedure. Embolic infarcts were defined as new foci of reduced diffusion and high signal intensity on fluid-attenuated inversion recovery brain MRI within a vascular distribution.The mean age was 58 years, half of the patients were men, half had a history of hypertension, and the majority had no known vascular disease or heart failure. LV ablation was performed in 12 patients (ventricular tachycardia, n=2; PVC, n=10) and right ventricular ablation was performed exclusively in 6 patients (ventricular tachycardia, n=1; PVC, n=5). Seven patients (58%) undergoing LV ablation experienced a total of 16 cerebral emboli, in comparison with zero patients undergoing right ventricular ablation (P=0.04). Seven of 11 patients (63%) undergoing a retrograde approach to the LV developed at least 1 new brain lesion.More than half of patients undergoing routine LV ablation procedures (predominately PVC ablations) experienced new brain emboli after the procedure. Future research is critical to understanding the long-term consequences of these lesions and to determining optimal strategies to avoid them.
View details for DOI 10.1161/CIRCULATIONAHA.116.025546
View details for Web of Science ID 000395549700014
View details for PubMedID 28119381
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The Wearable Cardioverter-Defibrillator Is It Now the Standard of Care?
CIRCULATION
2016; 134 (9): 644-646
View details for DOI 10.1161/CIRCULATIONAHA.116.024287
View details for Web of Science ID 000382288200009
View details for PubMedID 27572878
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Predicting Persistent Left Ventricular Dysfunction Following Myocardial Infarction The PREDICTS Study
JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
2016; 67 (10): 1186-1196
Abstract
Persistent severe left ventricular (LV) systolic dysfunction after myocardial infarction (MI) is associated with increased mortality and is a class I indication for implantation of a cardioverter-defibrillator.This study developed models and assessed independent predictors of LV recovery to >35% and ≥50% after 90-day follow-up in patients presenting with acute MI and severe LV dysfunction.Our multicenter prospective observational study enrolled participants with ejection fraction (EF) of ≤35% at the time of MI (n = 231). Predictors for EF recovery to >35% and ≥50% were identified after multivariate modeling and validated in a separate cohort (n = 236).In the PREDICTS (PREDiction of ICd Treatment Study) study, 43% of patients had persistent EF ≤35%, 31% had an EF of 36% to 49%, and 26% had an EF ≥50%. The model that best predicted recovery of EF to >35% included EF at presentation, length of stay, prior MI, lateral wall motion abnormality at presentation, and peak troponin. The model that best predicted recovery of EF to ≥50% included EF at presentation, peak troponin, prior MI, and presentation with ventricular fibrillation or cardiac arrest. After predictors were transformed into point scores, the lowest point scores predicted a 9% and 4% probability of EF recovery to >35% and ≥50%, respectively, whereas profiles with the highest point scores predicted an 87% and 49% probability of EF recovery to >35% and ≥50%, respectively.In patients with severe systolic dysfunction following acute MI with an EF ≤35%, 57% had EF recovery to >35%. A model using clinical variables present at the time of MI can help predict EF recovery.
View details for DOI 10.1016/j.jacc.2015.12.042
View details for Web of Science ID 000371398700009
View details for PubMedID 26965540
View details for PubMedCentralID PMC4854198
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Variable Clinical Features and Ablation of Manifest Nodofascicular/Ventricular Pathways
CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY
2015; 8 (1): 117-U185
Abstract
Manifest nodofascicular/ventricular (NFV) pathways are rare.From 2008 to 2013, 4 cases were identified with manifest NFV pathways from 3 centers. The clinical findings and ablation sites are reported. All 4 cases presented with a wide complex tachycardia but with different QRS morphologies. Case 1 showed a left bundle branch block/superior axis, case 2 showed a right bundle branch block/inferior axis, case 3 showed a left bundle branch block/inferior axis, and case 4 showed a narrow QRS tachycardia and a wide complex tachycardia with a left bundle branch block/inferior axis. Three of the 4 tachycardias had atrioventricular dissociation ruling out extranodal accessory pathways, including atriofascicular pathways. Programmed extrastimuli showed evidence of a decremental accessory pathway in 3 of the 4 cases. Coexisting tachycardia mechanisms were seen in 3 of the 4 cases (atrioventricular nodal reentry tachycardia [2] and atrioventricular reentrant tachycardia [1]). Ablation in the slow pathway region eliminated the NFV pathway in 3 (transient in 1) with the other responding to surgical closure of a large atrial septal defect. The NFV pathway was a critical part of the tachycardia circuit in 1 and proved to be a bystander in the other 3 cases.Manifest NFV pathways presented with variable QRS expression dependent on the ventricular insertion site and often coexisted with other tachycardia mechanisms (atrioventricular nodal reentry tachycardia and atrioventricular reentrant tachycardia). In most cases, the atrial insertion of the pathway was in or near the slow pathway region. The NFV pathways were either critical to the tachycardia circuit or served as bystanders.
View details for DOI 10.1161/CIRCEP.114.001924
View details for Web of Science ID 000349873000018
View details for PubMedID 25472957
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Funding source and author affiliation in TASER research are strongly associated with a conclusion of device safety
AMERICAN HEART JOURNAL
2011; 162 (3): 533-537
View details for DOI 10.1016/j.ahj.2011.05.025
View details for Web of Science ID 000294447400018
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Frequency of Atrial Flutter After Adult Lung Transplantation
AMERICAN JOURNAL OF CARDIOLOGY
2011; 107 (6): 922-926
Abstract
Lung transplantation, which involves an anastomosis of the graft to the native left atrium, may increase the risk of left-side atrial flutter (AFL). Our aim was to evaluate the incidence, predisposing conditions, and course of AFL after lung transplantation in adults. Two hundred sixty-nine consecutive patients who underwent lung transplantation were studied retrospectively. All patients received a preoperative echocardiogram and postoperative electrocardiographic monitoring. All 12-lead electrocardiograms were reviewed. Typical or atypical AFL was diagnosed by 2 independent reviewers based on accepted criteria. Predictors of AFL were investigated separately using univariate and multivariate logistic regression analyses. AFL occurred in 35 of 269 patients (13%) over a mean of 12 days after transplantation. All patients who developed AFL had no previous atrial arrhythmia. Of these 35 patients, 24 (68.6%) had atypical AFL by electrocardiographic criteria. In multivariate logistic regression analysis, patients with idiopathic pulmonary fibrosis (IPF) were 2.9 times more likely to have AFL than those patients with lung transplant without IPF (p = 0.009). Other independent risk factors for AFL were advanced age and preoperative left atrial enlargement. Only 3 of 35 patients (8.6%) with AFL had persistent atrial arrhythmia and needed electrophysiologic study and ablation. In conclusion, AFL is common soon after lung transplantation. Those with IPF, advanced age, or left atrial enlargement are at increased risk. In most cases, AFL is a self-limited arrhythmia that resolves spontaneously with no need for ablation.
View details for DOI 10.1016/j.amjcard.2010.10.076
View details for Web of Science ID 000288825300020
View details for PubMedID 21247524
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Approach to Cardiac Device Malfunction.
Cardiac electrophysiology clinics
2010; 2 (2): 267
Abstract
Dealing with cardiac device malfunctions can be fun. Most of the time, the cause of the patient's new symptom can be discovered and alleviated. The clinician needs to approach the patient in a step-by-step manner. A careful history and brief physical examination before device interrogation is important. Since cardiac devices are now incredibly complex, it is crucial for clinicians to be comfortable with calling on the device company's representative or its technical services for help.
View details for DOI 10.1016/j.ccep.2010.01.012
View details for PubMedID 28770760
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Intracardiac and extracardiac markers of inflammation during atrial fibrillation
HEART RHYTHM
2010; 7 (2): 149-154
Abstract
A decrease in inflammation after cure of atrial arrhythmias suggests that such arrhythmias are proinflammatory, and lower inflammatory marker levels in the coronary sinus suggest that atrial arrhythmias result in intracardiac appropriation of inflammatory cytokines.The purpose of this study was to investigate the effect of atrial fibrillation on inflammatory markers drawn from intracardiac and extracardiac chambers.We performed a case-control study of 167 AF patients and 207 controls. Blood from intracardiac and extracardiac sites was obtained from a subset of patients undergoing curative AF ablation (n = 46).No significant differences in C-reactive protein (CRP) or interleukin-6 (IL-6) levels were seen between patients with and those without a history of AF. Both levels were significantly higher when blood was drawn during AF than during sinus rhythm: median CRP 3.1 mg/dL (interquartile range [IQR] 1.0-6.0) versus 1.7 mg/dL (IQR 0.7-3.9, P = .0005); median IL-6 2.3 ng/mL (IQR 1.5-3.9) versus 1.5 ng/mL (IQR 0.7-2.5, P = .007). This finding persisted after adjusting for potential confounders. AF ablation patients in AF exhibited a positive median left atrial minus coronary sinus gradient CRP (0.3 mg/dL, IQR -0.03-1.1), whereas those in sinus rhythm had a negative median left atrial minus coronary sinus gradient CRP (-0.2, IQR -0.8-[-0.02], P = .01). Femoral artery minus femoral vein gradients in AF versus sinus rhythm did not show any differences.AF at the time of the blood draw, rather than a history of AF, was independently associated with inflammation. Differences in transcardiac gradients suggest that AF results in sequestration of inflammatory cytokines in the heart.
View details for DOI 10.1016/j.hrthm.2009.10.004
View details for Web of Science ID 000276189400001
View details for PubMedID 20022819
View details for PubMedCentralID PMC2900773
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Role of wearable and automatic external defibrillators in improving survival in patients at risk for sudden cardiac death.
Current treatment options in cardiovascular medicine
2009; 11 (5): 360-5
Abstract
Cardiac arrest is a vexing public health problem. Fortunately, implantable cardioverter-defibrillators (ICDs) have been proven to decrease overall mortality in several populations at high risk for cardiac arrest. However, it is still unclear how to treat patients who have an elevated risk of cardiac arrest but are not in one of the identified high-risk groups proven to benefit from an ICD. It also is uncertain how to manage high-risk patients who have an accepted indication for an ICD but are unable or unwilling to have an ICD. In these clinical situations, the wearable defibrillator and automatic external defibrillator are options that should be considered. Both devices have been shown in small series to be highly effective at restoring sinus rhythm in patients with a ventricular tachyarrhythmia. However, there is still a lack of large-scale trials proving that these devices should be employed routinely in specific high-risk patient populations.
View details for PubMedID 19846033
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Impact of advanced age on survival in patients with implantable cardioverter defibrillators
EUROPACE
2008; 10 (11): 1296-1301
Abstract
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
View details for PubMedCentralID PMC2721725
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QT Dispersion Is Not associated with Sudden Cardiac Death or Mortality in Heart Transplant Recipients
HEART SURGERY FORUM
2008; 11 (5): E281-E284
Abstract
Sudden cardiac death (SCD) has been shown to be a significant cause of death after heart transplantation. QT dispersion (QTd) is associated with SCD in several high-risk populations. We hypothesized that QTd would predict mortality and SCD in heart transplantation patients.We examined the clinical charts and most recent electrocardiograms (ECGs) for patients who received heart transplants at Stanford University Medical Center during the period 1981-1995. QTd was measured with all 12 leads and the precordial leads. Analysis was performed by a single reader blinded to patient outcomes.A total of 346 patients who had undergone transplantation had available ECGs and known outcomes; 155 of these patients died, and 42 of these deaths were attributed to SCD. The 12-lead mean QTd was not significantly different between outcome groups: patients who survived had a 12-lead mean QTd of 58 +/- 29 milliseconds and those who died had a 12-lead mean QTd of 61 +/- 32 milliseconds (P = .57). Patients who died from SCD had a 12-lead mean QTd of 57 +/- 31 milliseconds (P = .40), and those who died of other causes had a 12-lead mean QTd of 59 +/- 34 milliseconds (P = .36 vs those who died of SCD). Similarly, the precordial-lead mean QTd did not differ significantly between the different outcome groups.We found no correlation between QTd and SCD or mortality in heart transplant recipients. Until additional studies prove a positive association, QTd should not be used as a prognostic marker in these patients.
View details for DOI 10.1532/HSF98.20081023
View details for Web of Science ID 000265130200005
View details for PubMedID 18948241
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Episodic ventricular pacing with intact atrioventricular nodal function in a DDDR device: What is the rhythm and how can it be prevented?
HEART RHYTHM
2008; 5 (6): 897-898
View details for DOI 10.1016/j.hrthm.2008.02.031
View details for Web of Science ID 000256609200025
View details for PubMedID 18534376
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A first-degree family history in lone atrial fibrillation patients
HEART RHYTHM
2008; 5 (6): 826-830
Abstract
Atrial fibrillation (AF) may be due to an inherited trait, particularly in lone AF patients. A family history of AF in lone AF patients has not previously been compared with a family history of patients with AF and established risk factors (non-lone AF).The purpose of this study was to compare the frequency of having a first-degree relative with AF in lone and non-lone AF patients.We performed a case-control study of consecutive subjects presenting to a single electrophysiology laboratory. A convenience sample of subjects with no known arrhythmias was also enrolled.Four hundred twenty-nine subjects were enrolled: 136 had AF (54 with lone AF), 84 had atrial flutter, 158 had other supraventricular arrhythmias, and 51 had no known arrhythmias. Significantly more subjects with AF reported a first-degree family history of AF compared with the remainder of the cohort (25% vs. 5%; P <.001). In multivariable analysis adjusting for potential confounders, AF patients had a 6-fold greater odds of having a family member with AF (95% confidence interval [CI] 2.93-12.7; P <.001). Lone AF patients had a first-degree family member with AF substantially more often than those with non-lone AF (41% vs. 14%; P <.001). After adjusting for potential confounders, lone AF patients remained significantly more likely than other AF patients to have a first-degree relative with AF (OR 7.2; 95% CI 2.1-24.7; P = .002).Lone AF patients have a first-degree family member with AF substantially more often than other AF patients. This suggests that an inherited trait may be particularly important in this subgroup of patients.
View details for DOI 10.1016/j.hrthm.2008.02.016
View details for Web of Science ID 000256609200010
View details for PubMedID 18468961
View details for PubMedCentralID PMC2474569
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Alcohol intake is significantly associated with atrial flutter in patients under 60 years of age and a shorter right atrial effective refractory period
PACE-PACING AND CLINICAL ELECTROPHYSIOLOGY
2008; 31 (3): 266-272
View details for DOI 10.1111/j.1540-8159.2008.00985.x
View details for Web of Science ID 000253634600002
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Alcohol intake is significantly associated with atrial flutter in patients under 60 years of age and a shorter right atrial effective refractory period.
Pacing and clinical electrophysiology : PACE
2008; 31 (3): 266-72
Abstract
Although evidence suggests that alcohol is associated with atrial fibrillation (AF), the association between alcohol and atrial flutter (AFL) has not been examined. The mechanism connecting alcohol and atrial arrhythmias is unknown.Alcohol intake was determined in 195 consecutive patients with AF and AFL. Control subjects included patients with other supraventricular arrhythmias (n = 132) and healthy subjects (n = 54). Because of important competing risk factors for atrial arrhythmias in the elderly, stratification by age was performed. In a subset, atrial effective refractory periods (AERPs) were obtained from the high right atrium and proximal and distal coronary sinus.AF and AFL patients were significantly more likely to be daily alcohol drinkers (27% vs 14% of controls, P = 0.001). In multivariable analysis, AFL patients < or = 60 years of age were significantly more likely to be daily drinkers than to drink no alcohol compared to controls (odds ratio 17, 95% confidence interval 1.6-192.0, P = 0.019). Progressively more frequent alcohol intake was significantly associated with a progressively greater odds of AFL in patients < or = 60 years of age (P = 0.045). Neither AF subjects of any age nor AFL subjects > 60 years of age exhibited significant associations with alcohol after multivariable adjustment. Right AERPs shortened significantly with increasing amounts of alcohol intake (P = 0.025), whereas left AERPs were not associated with alcohol intake.Alcohol intake is positively associated with AFL in younger patients. The mechanism may be related to a shortening of the right AERP.
View details for DOI 10.1111/j.1540-8159.2008.00985.x
View details for PubMedID 18307620
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Markers of inflammation before and after curative ablation of atrial flutter
HEART RHYTHM
2008; 5 (2): 215-221
Abstract
Atrial arrhythmias are associated with inflammation. The cause and effect of the association are unknown.The purpose of this study was to test the hypothesis that atrial tachyarrhythmias contribute to inflammation.We performed a prospective observational study wherein C-reactive protein (CRP) and interleukin-6 (IL-6) levels from the femoral vein and coronary sinus (CS) were compared before curative ablation for atrial flutter (AFL; n = 59) and paroxysmal supraventricular tachycardia (SVT; n = 110). Follow-up levels were obtained at 1 and 6 months.Peripheral levels of both biomarkers were significantly higher in the AFL group. After multivariate adjustment, only those in the AFL group who presented in AFL or atrial fibrillation (AF) had significantly elevated CRP levels (odds ratio 1.26; P = .033). Levels of each marker were similar in the CS and peripheral blood in the SVT group; in the AFL group, both CRP and IL-6 were significantly lower in the CS than in the periphery (P = .0076 and P = .0021, respectively). CRP was significantly lower a median of 47 days after AFL ablation (from a median of 6.28 mg/L to a median of 2.92 mg/L; P = .028) and remained reduced at second follow-up. IL-6 decreased across three time points after AFL ablation (P = .002). No reduction in inflammatory biomarkers was observed after SVT ablation.CRP and IL-6 levels are elevated in patients presenting in AFL. Given the lower CS values in these patients, their origin appears to be systemic rather than cardiac. Because these levels significantly fall after ablation of AFL, the atrial tachyarrhythmia appears to be the cause (not the effect) of the inflammation.
View details for DOI 10.1016/j.hrthm.2007.10.007
View details for Web of Science ID 000253239100008
View details for PubMedID 18242542
View details for PubMedCentralID PMC2247371
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Inductionless or limited shock testing is possible in most patients with implantable cardioverter-defibrillators/cardiac resynchronization therapy defibrillators - Results of the multicenter ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation with Implantable Cardioverter-Defibrillator Implantations)
CIRCULATION
2007; 115 (18): 2382-2389
Abstract
Implantable cardioverter-defibrillators and cardiac resynchronization therapy defibrillators have relied on multiple ventricular fibrillation (VF) induction/defibrillation tests at implantation to ensure that the device can reliably sense, detect, and convert VF. The ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations) is the first large, multicenter, prospective trial comparing vulnerability safety margin testing versus defibrillation safety margin testing with a single VF induction/defibrillation.A total of 426 patients receiving an implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator underwent vulnerability safety margin or defibrillation safety margin screening at 14 J in a randomized order. After this, patients underwent confirmatory testing, which required 2 VF conversions without failure at < or = 21 J. Patients who passed their first 14-J and confirmatory tests, irrespective of the results of their second 14-J test, had their devices programmed to a 21-J shock for ventricular tachycardia (VT) or VF > or = 200 bpm and were followed up for 1 year. Of 420 patients who underwent 14-J vulnerability safety margin screening, 322 (76.7%) passed. Of these, 317 (98.4%) also passed 21-J confirmatory tests. Of 416 patients who underwent 14-J defibrillation safety margin screening, 343 (82.5%) passed, and 338 (98.5%) also passed 21-J confirmatory tests. Most clinical VT/VF episodes (32 of 37, or 86%) were terminated by the first shock, with no difference in first shock success. In all observed cases in which the first shock was unsuccessful, subsequent shocks terminated VT/VF without complication.Although spontaneous episodes of fast VT/VF were limited, there was no difference in the odds of first shock efficacy between groups. Screening with vulnerability safety margin or defibrillation safety margin may allow for inductionless or limited shock testing in most patients.
View details for DOI 10.1161/CIRCULATIONAHA.106.663112
View details for Web of Science ID 000246278000005
View details for PubMedID 17470697
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Screening for coronary artery disease after mediastinal irradiation for Hodgkin's disease
JOURNAL OF CLINICAL ONCOLOGY
2007; 25 (1): 43-49
Abstract
Incidental cardiac irradiation during treatment of thoracic neoplasms has increased risks for subsequent acute myocardial infarction or sudden cardiac death. Identifying patients who have a high risk for a coronary event may decrease morbidity and mortality. The objective of this study was to evaluate whether stress imaging can identify severe, unsuspected coronary stenoses in patients who had prior mediastinal irradiation for Hodgkin's disease.We enrolled 294 outpatients observed at a tertiary care cancer treatment center after mediastinal irradiation doses 35 Gy for Hodgkin's disease who had no known ischemic cardiac disease. Patients underwent stress echocardiography and radionuclide perfusion imaging at one stress session. Coronary angiography was performed at the discretion of the physician.Among the 294 participants, 63 (21.4%) had abnormal ventricular images at rest, suggesting prior myocardial injury. During stress testing, 42 patients (14%) developed perfusion defects (n = 26), impaired wall motion (n = 8), or both abnormalities (n = 8). Coronary angiography showed stenosis 50% in 22 patients (55%), less than 50% in nine patients (22.5%), and no stenosis in nine patients (22.5%). Screening led to bypass graft surgery in seven patients. Twenty-three patients developed coronary events during a median of 6.5 years of follow-up, with 10 acute myocardial infarctions (two fatal).Stress-induced signs of ischemia and significant coronary artery disease are highly prevalent after mediastinal irradiation in young patients. Stress testing identifies asymptomatic individuals at high risk for acute myocardial infarction or sudden cardiac death.
View details for DOI 10.1200/JCO.2006.07.0805
View details for Web of Science ID 000243725900009
View details for PubMedID 17194904
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Repeat transseptal catheterization after ablation for atrial fibrillation
JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY
2007; 18 (1): 55-59
Abstract
A substantial number of patients require a second left atrial procedure after ablation for atrial fibrillation (AF), either for left atrial flutter or recurrent AF. The success and complication rates of repeat transseptal catheterization in these patients are unknown. The aim of this study was to determine the difficulty and/or success rates of repeat transseptal catheterization after left atrial ablation for AF.Consecutive patients undergoing repeat left atrial procedures after ablation for AF over a 1-year period were enrolled. Difficulties with, success rates, and complications of the first and second transseptal catheterizations were recorded. Sixteen patients underwent a repeat transseptal catheterization. Of the 4 in whom the first procedure was performed with an ablation catheter across a patent foramen ovale (PFO), 3 required a transseptal puncture for their repeat procedure. The remaining 12 underwent transseptal puncture without difficulty for their first procedure, and, despite the same operators for each patient, the repeat transseptal was noted to be difficult in 5. Of those 5, the transseptal puncture was unsuccessful due to increased interatrial septal thickness in 2 patients. One repeat transseptal attempt was aborted after posterior right atrial puncture with the transseptal needle occurred, attributed to distorted interatrial septal anatomy not observed prior to the first case.Compared with the first procedure, repeat transseptal catheterization after ablation for AF, whether initially performed across a PFO or via a transseptal puncture, is more difficult, less often successful, and potentially associated with more complications.
View details for DOI 10.1111/j.1540-8167.2006.00657.x
View details for Web of Science ID 000242833000013
View details for PubMedID 17081207
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Prevalence, patterns of development, and prognosis of right bundle branch block in heart transplant recipients
AMERICAN JOURNAL OF CARDIOLOGY
2006; 98 (9): 1288-1290
Abstract
Right bundle branch block (RBBB) is the most common electrocardiographic abnormality in heart transplant recipients, but the cause remains unknown, data regarding the prognosis are conflicting, and all previous studies have been limited to <100 patients. This was a study of patients who underwent heart transplantation at Stanford University Medical Center from 1981 to 1995 with known outcomes and >or=2 available electrocardiograms (ECGs). Outcomes were assessed in those with and without conduction disturbances recorded from the ECGs closest to the time of transplantation and the most recent ECGs. Of the 322 heart transplant recipients studied, 141 (44%) died over a mean follow-up of 9 +/- 3.5 years, and 40 (13%) died of sudden cardiac death. In the first ECG obtained, a mean of 1.8 +/- 2.4 years after transplantation, 44 patients (14%) had incomplete RBBB and 26 (8%) had RBBB; in the second ECG, obtained a mean of 5.6 +/- 3.7 years after transplantation, 59 patients (18%) had incomplete RBBB and 63 (20%) had RBBB. Increasing time from transplantation was associated with a greater likelihood for RBBB on the first and second ECGs (p = 0.001 and p <0.0001, respectively). QRS duration, incomplete RBBB, RBBB, or the development of RBBB was not associated with mortality or sudden cardiac death. In conclusion, although RBBB was the most common electrocardiographic abnormality in our study, the prevalence was lower than previously reported. The cause of RBBB appears to be largely related to events that occur well after transplantation, and the prognosis is benign.
View details for Web of Science ID 000241982200037
View details for PubMedID 17056348
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Initiation of antidromic reciprocating tachycardia: What is the mechanism?
HEART RHYTHM
2006; 3 (7): 865
View details for DOI 10.1016/j.hrthm.2006.03.014
View details for Web of Science ID 000239045600025
View details for PubMedID 16818224
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Diastolic dysfunction after mediastinal irradiation
AMERICAN HEART JOURNAL
2005; 150 (5): 977-982
Abstract
Mediastinal irradiation is known to cause cardiac disease, but its effect on left ventricular diastolic function is unknown. The purpose of this study was to determine the prevalence of diastolic dysfunction and its association with prognosis in asymptomatic patients after mediastinal irradiation.We recruited 294 patients who had received at least 35 Gy to the mediastinum for treatment of Hodgkin disease. Each patient underwent resting echocardiography, stress echocardiography, and nuclear scintigraphy. Survival free from cardiac events was determined during 3.2 years of follow-up.The mean age of the included patients was 42 years, and 49% were male. Adequate measurements of diastolic function were obtained in 282 (97%) patients. Diastolic dysfunction was considered mild in 26 (9%) and moderate in 14 (5%). Exercise-induced ischemia was more common in patients with diastolic dysfunction (23%) than those with normal diastolic function (11%, P = .008). After adjustment for patient demographics, clinical characteristics, and radiation history, patients with diastolic dysfunction had worse event-free survival than patients with normal function (hazard ratio 1.66, 95% CI 1.06-2.4).There is a high prevalence of diastolic dysfunction in asymptomatic patients after mediastinal irradiation, and the presence of diastolic dysfunction is associated with stress-induced ischemia and a worse prognosis. Screening with Doppler echocardiography may be helpful in identifying patients at risk for subsequent cardiac events.
View details for DOI 10.1016/j.ahj.2004.12.026
View details for Web of Science ID 000233478800024
View details for PubMedID 16290974
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A unique method by which to quantitate synchrony with equilibrium radionuclide angiography
JOURNAL OF NUCLEAR CARDIOLOGY
2005; 12 (4): 441-450
Abstract
Cardiac resynchronization therapy (CRT) improves symptoms and the survival rate in patients with advanced heart failure by improving synchrony. However, CRT is not always successful, is costly, and is applied without individualization. There is no specific measure of synchrony. The goal of this study was to analyze new quantitative parameters of synchrony and compare them with established measures.Equilibrium radionuclide angiography, phase angle (Ø), and amplitude quantitate regional contraction timing and magnitude and are the basis for new synchrony (S) and entropy (E) parameters. S is the vector sum of all amplitudes based on the angular distribution of Ø divided by the scalar sum of the length of all vectors. Complete S equals 1, and its absence equals 0. E measures the disorder in the region of interest, is 1 with random contraction and 0 with full synchrony, and differentiates among differing contraction patterns. Left ventricular S and E were measured in 22 normal equilibrium radionuclide angiography studies, where regions of interest were drawn from the left ventricle, left atrium, and background to analyze model ventricles with normal wall motion (N), ventricles with aneurysm (An), ventricles with severe diffuse dysfunction (Diff), and ventricles with severe regional dysfunction (Reg). The new S and E parameters were highly reproducible and well differentiated among N, An, Diff, and Reg, which were not separated by SD Ø (SD of ventricular phase), which has gained popularity as a measure of synchrony.Unique scintigraphic parameters for the evaluation of ventricular synchrony were derived, and their added value was determine compared with established measures. Indications for pacemaker therapy now include the treatment of severe congestive heart failure (CHF). Atrial triggered biventricular pacemakers reduce CHF symptoms and prolong life in patients with cardiomyopathy, severe CHF, left ventricular (LV) ejection fraction (EF) lower than 35%, and QRS greater than 120 milliseconds. Such pacing, or cardiac resynchronization therapy (CRT), seeks to reduce the heterogeneity and increase the synchrony of ventricular activation, conduction, and contraction. CRT has improved hemodynamics, increased exercise tolerance, reduced symptoms and the need for hospitalization, reversed ventricular remodeling, and reduced the all-cause mortality rate in CHF. However, CRT is costly, fails to improve symptoms or activity level in more than 30% of patients, and is applied blindly without individualization or consideration of lead placement sight. A variety of echocardiographic methods have sought to measure synchrony and its serial changes with CRT. A recent study presented evidence of the poor reproducibility of several widely applied echocardiographic measurements by which to determine ventricular synchrony. Magnetic resonance imaging has excellent resolution of regional wall motion and has been applied to assess ventricular synchrony and its response to pacing therapy. However, these methods are complex and are not well established or widely available, and magnetic resonance imaging has not been widely applied after pacing. An accurate and reproducible method is needed by which to objectively measure regional ventricular synchrony. Phase image analysis, a functional method based on the first Fourier harmonic fit of the gated blood pool time versus radioactivity curve, generates the parameters of amplitude (A), which parallels the extent of regional ventricular contraction or stroke volume, and phase angle (Ø), which represents the timing of regional contraction. It was applied early with demonstrated reproducibility to show the linkage between electrical and mechanical dyssynchrony and to characterize the contraction pattern in heart failure and its alteration with CRT. The SD of ventricular Ø, applied as a marker of synchrony, has been shown to demonstrate the beneficial effects of biventricular pacing, and its strong prognostic value has been shown in patients with congestive cardiomyopathy and CHF, superior to LVEF. The SD Ø may not be optimal for synchrony evaluation. We sought improved, more sensitive parameters to better differentiate synchrony among the spectrum of possible patterns of dyssynergy. We derived, initially evaluated, and here present new synchrony (S) and entropy (E) parameters, based on the phase method, to quantitate regional and global ventricular synchrony and applied them in simulation and clinical protocols.
View details for DOI 10.1016/j.nuclcard.2005.05.006
View details for Web of Science ID 000230993600011
View details for PubMedID 16084433
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Asymptomatic cardiac disease following mediastinal irradiation
JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY
2003; 42 (4): 743-749
Abstract
This study was designed to evaluate the potential benefit of screening previously irradiated patients with echocardiography.Mediastinal irradiation is known to cause cardiac disease. However, the prevalence of asymptomatic cardiac disease and the potential for intervention before symptom development are unknown.We recruited 294 asymptomatic patients (mean age 42 +/- 9 years, 49% men, mean mantle irradiation dose 43 +/- 0.3 Gy) treated with at least 35 Gy to the mediastinum for Hodgkin's disease. After providing written consent, each patient underwent electrocardiography and transthoracic echocardiography. Valvular disease was common and increased with time following irradiation. Patients who had received irradiation more than 20 years before evaluation had significantly more mild or greater aortic regurgitation (60% vs. 4%, p < 0.0001), moderate or greater tricuspid regurgitation (4% vs. 0%, p = 0.06), and aortic stenosis (16% vs. 0%, p = 0.0008) than those who had received irradiation within 10 years. The number needed to screen to detect one candidate for endocarditis prophylaxis was 13 (95% confidence interval [CI] 7 to 44) for patients treated within 10 years and 1.6 (95% CI 1.3 to 1.9) for those treated at least 20 years ago. Compared with the Framingham Heart Study population, mildly reduced left ventricular fractional shortening (<30%) was more common (36% vs. 3%), and age- and gender-adjusted left ventricular mass was lower (90 +/- 27 g/m vs. 117 g/m) in irradiated patients.There is a high prevalence of asymptomatic heart disease in general, and aortic valvular disease in particular, following mediastinal irradiation. Screening echocardiography should be considered for patients with a history of mediastinal irradiation.
View details for DOI 10.1016/S0735-1097(03)00759-9
View details for Web of Science ID 000184780600027
View details for PubMedID 12932613
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Cost-effectiveness of radiofrequency ablation for supraventricular tachycardia
ANNALS OF INTERNAL MEDICINE
2000; 133 (11): 864-876
Abstract
Radiofrequency ablation is an established but expensive treatment option for many forms of supraventricular tachycardia. Most cases of supraventricular tachycardia are not life-threatening; the goal of therapy is therefore to improve the patient's quality of life.To compare the cost-effectiveness of radiofrequency ablation with that of medical management of supraventricular tachycardia.Markov model.Costs were estimated from a major academic hospital and the literature, and treatment efficacy was estimated from reports from clinical studies at major medical centers. Probabilities of clinical outcomes were estimated from the literature. To account for the effect of radiofrequency ablation on quality of life, assessments by patients who had undergone the procedure were used.Cohort of symptomatic patients who experienced 4.6 unscheduled visits per year to an emergency department or a physician's office while receiving long-term drug therapy for supraventricular tachycardia.Patient lifetime.Societal.Initial radiofrequency ablation, long-term antiarrhythmic drug therapy, and treatment of acute episodes of arrhythmia with antiarrhythmic drugs.Costs, quality-adjusted life-years, life-years, and marginal cost-effectiveness ratios.Among patients who have monthly episodes of supraventricular tachycardia, radiofrequency ablation was the most effective and least expensive therapy and therefore dominated the drug therapy options. Radiofrequency ablation improved quality-adjusted life expectancy by 3.10 quality-adjusted life-years and reduced lifetime medical expenditures by $27 900 compared with long-term drug therapy. Long-term drug therapy was more effective and had lower costs than episodic drug therapy.The findings were highly robust over substantial variations in assumptions about the efficacy and complication rate of radiofrequency ablation, including analyses in which the complication rate was tripled and efficacy was decreased substantially.Radiofrequency ablation substantially improves quality of life and reduces costs when it is used to treat highly symptomatic patients. Although the benefit of radiofrequency ablation has not been studied in less symptomatic patients, a small improvement in quality of life is sufficient to give preference to radiofrequency ablation over drug therapy.
View details for PubMedID 11103056
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Meta-analysis of trials comparing beta-blockers, calcium antagonists, and nitrates for stable angina
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION
1999; 281 (20): 1927-1936
Abstract
Which drug is most effective as a first-line treatment for stable angina is not known.To compare the relative efficacy and tolerability of treatment with beta-blockers, calcium antagonists, and long-acting nitrates for patients who have stable angina.We identified English-language studies published between 1966 and 1997 by searching the MEDLINE and EMBASE databases and reviewing the bibliographies of identified articles to locate additional relevant studies.Randomized or crossover studies comparing antianginal drugs from 2 or 3 different classes (beta-blockers, calcium antagonists, and long-acting nitrates) lasting at least 1 week were reviewed. Studies were selected if they reported at least 1 of the following outcomes: cardiac death, myocardial infarction, study withdrawal due to adverse events, angina frequency, nitroglycerin use, or exercise duration. Ninety (63%) of 143 identified studies met the inclusion criteria.Two independent reviewers extracted data from selected articles, settling any differences by consensus. Outcome data were extracted a third time by 1 of the investigators. We combined results using odds ratios (ORs) for discrete data and mean differences for continuous data. Studies of calcium antagonists were grouped by duration and type of drug (nifedipine vs nonnifedipine).Rates of cardiac death and myocardial infarction were not significantly different for treatment with beta-blockers vs calcium antagonists (OR, 0.97; 95% confidence interval [CI], 0.67-1.38; P = .79). There were 0.31 (95% CI, 0.00-0.62; P = .05) fewer episodes of angina per week with beta-blockers than with calcium antagonists. beta-Blockers were discontinued because of adverse events less often than were calcium antagonists (OR, 0.72; 95% CI, 0.60-0.86; P<.001). The differences between beta-blockers and calcium antagonists were most striking for nifedipine (OR for adverse events with beta-blockers vs nifedipine, 0.60; 95% CI, 0.47-0.77). Too few trials compared nitrates with calcium antagonists or beta-blockers to draw firm conclusions about relative efficacy.beta-Blockers provide similar clinical outcomes and are associated with fewer adverse events than calcium antagonists in randomized trials of patients who have stable angina.
View details for Web of Science ID 000080427300033
View details for PubMedID 10349897
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Lemierre's syndrome
SOUTHERN MEDICAL JOURNAL
1997; 90 (6): 640-643
Abstract
Lemierre's syndrome is an acute medical condition characterized by anaerobic oropharyngeal infection leading to septic thrombophlebitis of the internal jugular vein. The illness is often complicated by septic pulmonary emboli and distant metastatic infections. Treatment consists of surgical drainage of purulent collections and long-term intravenous antibiotic therapy. Although Lemierre's syndrome is rare, it is potentially fatal and remains an important entity for clinicians to recognize and treat appropriately.
View details for Web of Science ID A1997XE84400013
View details for PubMedID 9191743