Assistant Professor - Med Center Line, Medicine - Cardiovascular Medicine
Director of Interventional Cardiology, VA Palo Alto Healthcare System (2018 - Present)
Honors & Awards
HSR&D Career Development Award, Veterans Health Administration (2019-pres)
AHA Mentored Clinical & Population Research Award, American Heart Association (2016-pres)
ACCF/Merck Cardiovascular Research Fellow, American College of Cardiology Foundation (2013-2014)
Soros Fellow, Paul & Daisy Soros Fellowship for New Americans (2003-2005)
British Marshall Scholar, Marshall Aid Commemoration Commission (2001-2003)
Boards, Advisory Committees, Professional Organizations
Board of Directors, American College of Cardiology, California Chapter (2018 - Present)
Fellowship, Stanford University School of Medicine, Interventional Cardiology (2015)
Fellowship, Stanford University School of Medicine, Cardiology (2013)
Residency, University of California, San Francisco, Internal Medicine (2010)
MD, Stanford School of Medicine (2007)
MBA, Oxford University (2003)
MSc, London School of Economics, Health Policy, Planning & Financing (2002)
BS, University of California, Berkeley, Molecular Environmental Biology (2001)
Sex Differences in the Pursuit of Interventional Cardiology as a Subspecialty Among CardiovascularFellows-in-Training.
JACC. Cardiovascular interventions
OBJECTIVES: The authors sought to determine the factors that influence fellows-in-training (FITs) to pursue a career in interventional cardiology (IC) and how these differ by sex.BACKGROUND: Despite increases in the proportion of women across numerous medical and surgical specialties over the last decade, IC still ranks at the bottom in terms of representation of women. It is unclear why this maldistribution persists.METHODS: An online survey of cardiovascular FITs was conducted under the direction of the American College of Cardiology Women in Cardiology Leadership Council to assess FIT perspectives regarding subspecialty choices.RESULTS: Of 574 respondents, 33% anticipated specializing in IC. Men were more likely to choose IC than women (39% men, 17% women, odds ratio: 3.98 [95% confidence interval: 2.38 to 6.68]; p< 0.001). Men were more likely to be married (p= 0.005) and have children (p= 0.002). Among married FITs, male IC FITs were more likely to have spouses who do not work (p= 0.003). Although men were more likely to be influenced by positive attributes to pursue IC, women were significantly more likely to be influenced negatively against pursuing the field by attributes including greater interest in another field (p= 0.001), little job flexibility (p= 0.02), physically demanding nature of job (p=0.004), radiation during childbearing (p< 0.001), "old boys' club" culture (p< 0.001), lack of female role models (p< 0.001), and sex discrimination (p< 0.001).CONCLUSIONS: Many factors uniquely dissuade women from pursuing IC compared with men, largely related to the culture of IC as a subspecialty. Targeted resolution of these specific factors may provide the most impact in reducing sex imbalances in the field.
View details for DOI 10.1016/j.jcin.2018.09.036
View details for PubMedID 30660463
Racial Differences in Quality of Care and Outcomes After Acute Coronary Syndrome.
The American journal of cardiology
Guideline adherence and variation in acute coronary syndrome (ACS) outcomes by race in the modern era of drug-eluting stents (DES) are not well understood. Previous studies also fail to capture rapidly growing minority populations, such as Asians. A retrospective analysis of 689,238 hospitalizations for ACS across all insurance types from 2008 to 2011 from the Healthcare Cost and Utilization Project database was performed to determine whether quality of ACS care and mortality differ by race (white, black, Asian, Hispanic, or Native American), with adjustment for patient clinical and demographic characteristics and clustering by hospital. We found that black patients had the lowest in-hospital mortality rates (5% vs 6% to 7% for other races, p<0.0001, odds ratio [OR] 1.02, 95% confidence interval [CI] 0.97 to 1.07), despite low rates of timely angiography in ST-elevation myocardial infarction and non-ST-elevation myocardial infarction, and lower use of DES (30% vs 38% to 40% for other races, p<0.0001). In contrast, Asian patients had the highest in-hospital mortality rates (7% vs 5% to 7% for other races, p<0.0001, odds ratio 1.13, 95% CI 1.08 to 1.20, relative to white patients), despite higher rates of timely angiography in ST-elevation myocardial infarction and non-ST-elevation myocardial infarction, and the highest use of DES (74% vs 63% to 68% for other races, p<0.0001). Asian patients had the worst in-hospital mortality outcomes after ACS, despite high use of early invasive treatments. Black patients had better in-hospital outcomes despite receiving less guideline-driven care.
View details for DOI 10.1016/j.amjcard.2018.02.036
View details for PubMedID 29655881
- THE EFFICACY AND SAFETY OF CANGRELOR FOR PATIENTS UNDERGOING SINGLE VESSEL VERSUS MULTI VESSEL PERCUTANEOUS CORONARY INTERVENTION: INSIGHTS FROM THE CHAMPION PHOENIX TRIAL ELSEVIER SCIENCE INC. 2018: 29
- Association of insurance type with receipt of oral anticoagulation in insured patients with atrial fibrillation: A report from the American College of Cardiology NCDR PINNACLE registry AMERICAN HEART JOURNAL 2018; 195: 50–59
Cangrelor reduces the risk of ischemic complications in patients with single-vessel and multi-vessel disease undergoing percutaneous coronary intervention: Insights from the CHAMPION PHOENIX trial.
American heart journal
2017; 188: 147-155
To examine the safety and efficacy of cangrelor in patients with single-vessel disease (SVD) and multi-vessel disease (MVD).Cangrelor, an intravenous, rapidly acting P2Y12 inhibitor, is superior to clopidogrel in reducing ischemic events among patients receiving percutaneous coronary intervention (PCI).We studied a modified intention to treat population of patients with SVD and MVD from the CHAMPION PHOENIX trial. The primary efficacy outcome was the composite of death, myocardial infarction (MI), ischemia-driven revascularization (IDR), and stent thrombosis (ST) at 48hours. The key safety outcome was non-coronary artery bypass grafting GUSTO severe bleeding at 48hours.Among 10,921 patients, 5,220 (48%) had SVD and 5,701 (52%) had MVD. MVD patients were older and more often had diabetes, hyperlipidemia, hypertension, prior stroke, and prior MI. After adjustment, MVD patients had similar rates of 48-hour death/MI/IDR/ST (6.3% vs 4.2%, adjusted odds ratio [OR] 1.6 [95% CI 0.42-6.06]) and GUSTO severe bleeding (0.1% vs 0.2%, P=.67) compared with SVD patients. Consistent with overall trial findings, cangrelor use reduced ischemic complications in patients with both SVD (3.9% vs 4.5%; OR 0.86, 95% CI 0.65-1.12) and MVD (5.5% vs 7.2%; OR 0.74, 95% CI 0.6-0.92, P-interaction=.43). GUSTO severe bleeding outcomes were not significantly increased with cangrelor or clopidogrel in either SVD or MVD patients.In the CHAMPION PHOENIX trial, MVD and SVD patients had similar ischemic outcomes at 48hours and 30days. Cangrelor consistently reduced ischemic complications in both SVD and MVD patients without a significant increase in GUSTO severe bleeding. CLINICAL PERSPECTIVES.
View details for DOI 10.1016/j.ahj.2017.02.031
View details for PubMedID 28577670
Impact of Baseline Stroke Risk and Bleeding Risk on Warfarin International Normalized Ratio Control in Atrial Fibrillation (from the TREAT-AF Study)
AMERICAN JOURNAL OF CARDIOLOGY
2017; 119 (2): 268-274
Warfarin prevents stroke and prolongs survival in patients with atrial fibrillation and flutter (AF, collectively) but can cause hemorrhage. The time in international normalized ratio (INR) therapeutic range (TTR) mediates stroke reduction and bleeding risk. This study sought to determine the relation between baseline stroke, bleeding risk, and TTR. Using data from The Retrospective Evaluation and Assessment of Therapies in Atrial Fibrillation (TREAT-AF) retrospective cohort study, national Veterans Health Administration records were used to identify patients with newly diagnosed AF from 2003 to 2012 and subsequent initiation of warfarin. Baseline stroke and bleeding risk was determined by calculating CHA2DS2-VASc and HAS-BLED scores, respectively. Main outcomes were first-year and long-term TTR and INR monitoring rate. In 167,190 patients, the proportion of patients with TTR (>65%) decreased across increasing strata of CHA2DS2-VASc and HAS-BLED. After covariate adjustment, odds of achieving TTR >65% were significantly associated with high CHA2DS2-VASc or HAS-BLED score. INR monitoring rate was similar across risk strata. In conclusion, increased baseline stroke and bleeding risk is associated with poor INR control, despite similar rates of INR monitoring. These findings may paradoxically limit warfarin's efficacy and safety in high-risk patients and may explain observed increased bleeding and stroke rates in this cohort.
View details for DOI 10.1016/j.amjcard.2016.09.045
View details for Web of Science ID 000392896900016
View details for PubMedID 27836133
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
- The Evolution of Temporary Percutaneous Mechanical Circulatory Support Devices: a Review of the Options and Evidence in Cardiogenic Shock CURRENT CARDIOLOGY REPORTS 2015; 17 (6)
Socioeconomic Inequalities in Quality of Care and Outcomes Among Patients With Acute Coronary Syndrome in the Modern Era of Drug Eluting Stents
JOURNAL OF THE AMERICAN HEART ASSOCIATION
2014; 3 (6)
The rapidly changing landscape of percutaneous coronary intervention provides a unique model for examining disparities over time. Previous studies have not examined socioeconomic inequalities in the current era of drug eluting stents (DES).We analyzed 835 070 hospitalizations for acute coronary syndrome (ACS) from the Healthcare Cost and Utilization Project across all insurance types from 2008 to 2011, examining whether quality of care and outcomes for patients with ACS differed by income (based on zip code of residence) with adjustment for patient characteristics and clustering by hospital. We found that lower-income patients were less likely to receive an angiogram within 24 hours of a ST elevation myocardial infarction (STEMI) (69.5% for IQ1 versus 73.7% for IQ4, P<0.0001, OR 0.79 [0.68 to 0.91]) or within 48 hours of a Non-STEMI (47.6% for IQ1 versus 51.8% for IQ4, P<0.0001, OR 0.86 [0.75 to 0.99]). Lower income was associated with less use of a DES (64.7% for IQ1 versus 71.2% for IQ4, P<0.0001, OR 0.83 [0.74 to 0.93]). However, no differences were found for coronary artery bypass surgery. Among STEMI patients, lower-income patients also had slightly increased adjusted mortality rates (10.8% for IQ1 versus 9.4% for IQ4, P<0.0001, OR 1.17 [1.11 to 1.25]). After further adjusting for time to reperfusion among STEMI patients, mortality differences across income groups decreased.For the most well accepted procedural treatments for ACS, income inequalities have faded. However, such inequalities have persisted for DES use, a relatively expensive and until recently, controversial revascularization procedure. Differences in mortality are significantly associated with differences in time to primary PCI, suggesting an important target for understanding why these inequalities persist.
View details for DOI 10.1161/JAHA.114.001029
View details for Web of Science ID 000345067600027
View details for PubMedID 25398888
View details for PubMedCentralID PMC4338689
Justification of an Introductory Electrocardiogram Teaching Mnemonic by Demonstration of its Prognostic Value
AMERICAN JOURNAL OF MEDICINE
2014; 127 (12): 1202-1207
With diminishing time afforded to electrocardiography in the medical curriculum, we have found Sibbitt's simple mnemonic, the Diagonal Line Lead Rule, for a pattern recognition approach to 12-lead electrocardiogram (ECG) interpretation to be appreciated by students. However, it still lacks universal acceptance because its clinical utility has not been documented. The study objective was to demonstrate the clinical utility of the Diagonal Line Lead ECG Teaching Rule.After excluding ECGs of high-risk patients with Wolff-Parkinson-White syndrome and QRS durations greater than 120 ms, the initial ECGs of the remaining 43,798 patients were scored according to the Diagonal Line Lead Rule. A total of 45,497 patients from the Veterans Affairs Palo Alto Healthcare System were referred for a routine initial resting ECG from 1987 to 1999. We determined cardiovascular mortality with 8 years of follow-up.In patients with normal QRS duration, diagnostic Q-wave or T-wave inversions isolated to the diagonal line leads showed no increased risk of cardiovascular death. Q-wave or T-wave inversion in any other lead was significantly associated with cardiovascular death with an age-adjusted Cox hazard of 2.6 (confidence interval, 2.4-2.8; P < .0001) and an annual cardiovascular mortality rate of 3.0%. Leads V4-V6, I, and aVL were especially significant predictors of cardiovascular death, with a Cox hazard greater than 3.Our analysis demonstrates the prognostic power and clinical utility of a simple mnemonic for 12-lead ECG interpretation that can facilitate ECG teaching and interpretation.
View details for DOI 10.1016/j.amjmed.2014.07.016
View details for Web of Science ID 000346029400038
View details for PubMedID 25065339
Transcatheter CoreValve valve-in-valve implantation in a stentless porcine aortic valve for severe aortic regurgitation.
Clinical case reports
2014; 2 (6): 281-285
We describe the first valve-in-valve Corevalve transcatheter aortic valve replacement in the St. Jude Toronto stentless porcine aortic valve in the United States, which enabled this 59-year-old patient with a history of bacterial endocarditis and aortic regurgitation to avoid heart transplant with complete resolution of his severe left ventricular dysfunction.
View details for DOI 10.1002/ccr3.113
View details for PubMedID 25548631
Patterns and prognosis of all components of the J-wave pattern in multiethnic athletes and ambulatory patients.
American heart journal
2014; 167 (2): 259-266
Despite recent concern about the significance of the J-wave pattern (also often referred to as early repolarization) and the importance of screening in athletes, there are limited rigorous prognostic data characterizing the 3 components of the J-wave pattern (ST elevation, J waves, and QRS slurs). We aim to assess the prevalence, patterns, and prognosis of the J-wave pattern among both stable clinical and athlete populations.We retrospectively studied 4,041 electrocardiograms from a multiethnic clinical population from 1997 to 1999 at the Veterans Affairs Palo Alto Health Care System. We also examined preparticipation electrocardiograms of 1,114 Stanford University varsity athletes from 2007 to 2008. Strictly defined criteria for components of the J-wave pattern were examined. In clinical subjects, prognosis was assessed using the end point of cardiovascular death after 7 years of follow-up.Components of the J-wave pattern were most prevalent in males; African Americans; and, particularly, athletes, with the greatest variations demonstrated in the lateral leads. ST elevation was the most common. Inferior J waves and slurs, previously linked to cardiovascular risk, were observed in 9.6% of clinical subjects and 12.3% of athletes. J waves, slurs, or ST elevation was not associated with time to cardiovascular death in clinical subjects, and ST-segment slope abnormalities were not prevalent enough in conjunction with them to reach significance.J waves, slurs, or ST elevation was not associated with increased hazard of cardiovascular death in our large multiethnic, ambulatory population. Even subsets of J-wave patterns, recently proposed to pose a risk of arrhythmic death, occurred at such a high prevalence as to negate their utility in screening.
View details for DOI 10.1016/j.ahj.2013.10.027
View details for PubMedID 24439988
- Prognostic implications of the J wave ECG patterns. Journal of electrocardiology 2013; 46 (5): 408-410
- Variability in quantitative and qualitative analysis of intravascular ultrasound and frequency domain optical coherence tomography CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS 2013; 82 (3): E192-E199
- J wave patterns and ST elevation in women. Journal of electrocardiology 2013; 46 (5): 417-423
- The Electrocardiogram at a Crossroads CIRCULATION 2013; 128 (1): 79-82
A novel stress echocardiography pattern for myocardial bridge with invasive structural and hemodynamic correlation.
Journal of the American Heart Association
2013; 2 (2)
Patients with a myocardial bridge (MB) and no significant obstructive coronary artery disease (CAD) may experience angina presumably from ischemia, but noninvasive assessment has been limited and the underlying mechanism poorly understood. This study seeks to correlate a novel exercise echocardiography (EE) finding for MBs with invasive structural and hemodynamic measurements.Eighteen patients with angina and an EE pattern of focal end-systolic to early-diastolic buckling in the septum with apical sparing were prospectively enrolled for invasive assessment. This included coronary angiography, left anterior descending artery (LAD) intravascular ultrasound (IVUS), and intracoronary pressure and Doppler measurements at rest and during dobutamine stress. All patients were found to have an LAD MB on IVUS. The ratios of diastolic intracoronary pressure divided by aortic pressure at rest (Pd/Pa) and during dobutamine stress (diastolic fractional flow reserve [dFFR]) and peak Doppler flow velocity recordings at rest and with stress were successfully performed in 14 patients. All had abnormal dFFR (≤0.75) at stress within the bridge, distally or in both positions, and on average showed a more than doubling in peak Doppler flow velocity inside the MB at stress. Seventy-five percent of patients had normalization of dFFR distal to the MB, with partial pressure recovery and a decrease in peak Doppler flow velocity.A distinctive septal wall motion abnormality with apical sparing on EE is associated with a documented MB by IVUS and a decreased dFFR. We posit that the septal wall motion abnormality on EE is due to dynamic ischemia local to the compressed segment of the LAD from the increase in velocity and decrease in perfusion pressure, consistent with the Venturi effect.
View details for DOI 10.1161/JAHA.113.000097
View details for PubMedID 23591827
View details for PubMedCentralID PMC3647262
- A novel stress echocardiography pattern for myocardial bridge with invasive structural and hemodynamic correlation. Journal of the American Heart Association 2013; 2 (2)
International differences in patient and physician perceptions of "high quality" healthcare: A model from pediatric cardiology
AMERICAN JOURNAL OF CARDIOLOGY
2006; 97 (7): 1073-1075
Although the quality of health care would logically seem to be a universal concept, this study hypothesized that physicians and their patients could differ in their perceptions of "high-quality care" and that those beliefs might vary by country. Such a mismatch in beliefs may be especially important as clinical practice guidelines developed in the United States are globalized. A survey of 20 statements describing various components of health care delivery and quality was sent to pediatric cardiologists in 33 countries, who ranked the statements in order of priority for ideal health care. Each participating physician administered the questionnaire to the parents of children with congenital heart disease; 554 questionnaires were received and analyzed. A subanalysis of 9 countries with the largest number of responses was done (Canada, the Czech Republic, France, Germany, Italy, The Netherlands, Sweden, the United Kingdom, and the United States). Doctors and parents rated the same 4 statements among the top 5: "the doctor is skillful and knowledgeable"; "the doctor explains health problems, tests, and treatments in a way the patient can understand"; "a basic level of healthcare is available to all citizens regardless of their ability to pay"; and "treatment causes the patient to feel physically well." Overall, parents' responses differed more among countries than those of physicians; the magnitude of the difference between parents and physicians varied by country. This discrepancy highlights a potential mismatch between patients' and physicians' views about the desired components of health care delivery, in particular the application of American quality standards for health care to systems in other countries.
View details for DOI 10.1016/j.amjcard.2005.10.051
View details for Web of Science ID 000236708700029
View details for PubMedID 16563919