Sheldon M Singh

McMaster University, Hamilton, Ontario, Canada

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Publications (53)235.28 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Little data exists on procedural/biophysical indicators of pulmonary vein (PV) isolation durability following cryoballoon ablation of atrial fibrillation (AF). Objective: This study investigated the procedural/biophysical characteristics associated with late PV reconnection (PVR) and durable PV isolation (PVI) following cryoablation using the currently-available second-generation cryoballoon. Methods: Data from 435 PVs targeted in 112 consecutive patients who underwent a repeat procedure 14±3 months following an index cryoablation of AF, were examined. Results: Altogether, 111 PVs (25.5%) in 71 patients (63.4%) demonstrated PVR, whereas 324 PVs (74.5%) exhibited PVI. The number and duration of cryoapplications did not differ between PVR and PVI. However, the time-to-PV isolation (time-to-effect) was considerably shorter (39.1±11.7 sec vs. 67.6±19.7 sec; p<0.001), the balloon temperature at time-to-effect significantly warmer (-32.1±7.8⁰C vs. -39.4±5.8⁰C; p<0.001), the balloon nadir temperature (-48.7±4.6⁰C vs. -47.8±2.9⁰C; p=0.034) slightly cooler, and the total thaw time (56.5±25.4 sec vs. 34.8±9.1 sec; p<0.001) and interval thaw times at 0°C (iTT0, 14.8±10.9 sec vs. 7.1±2.0 sec; p<0.001) and 15°C (iTT15, 54.2±25.4 sec vs. 33.3±9.1 sec; p<0.001) were notably longer with PVI, compared to PVR. However, only a time-to-effect ≤60 sec and an iTT0 ≥10 sec emerged as significant predictors of PV isolation durability. Consequently, in a multivariate model, presence of both criteria predicted <1% and their mere absence ~75% likelihood of late PV reconnection. Conclusions: A time-to-effect ≤60 sec and an iTT0 ≥10 sec significantly predict PV isolation durability following cryoballoon ablation of AF. If both criteria are met, the likelihood of PV reconnection may be exceedingly low.
    Heart rhythm: the official journal of the Heart Rhythm Society 11/2015; DOI:10.1016/j.hrthm.2015.10.033 · 5.08 Impact Factor

  • Journal of the American College of Cardiology 10/2015; 66(15):B297. DOI:10.1016/j.jacc.2015.08.749 · 16.50 Impact Factor
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    ABSTRACT: Background: Multiple studies have demonstrated a reduction of cardiovascular events in patients who receive the annual influenza vaccine. Despite recommendations from cardiovascular societies, influenza vaccination remains suboptimal in the implantable cardioverter defibrillator (ICD) population. Barriers to receiving the influenza vaccination have not been explored. Purpose: To evaluate the barriers to receiving the influenza vaccine in patients with ICDs. Design: Exploratory descriptive design using a survey developed by the staff of the ICD clinic. Procedure: A pilot study was conducted as part of a quality initiative of ICD patients at a regional cardiac centre. These patients were approached to participate in a one-page survey assessing barriers to receipt of the influenza vaccination. Predictors of vaccination were determined using multivariate logistic regression. Findings: Of the 229 patients who completed the survey between September 1 and November 31, 2011, 78% of the patients received the influenza vaccine. The only factor independently associated with influenza vaccination was a positive patient attitude toward the safety of influenza vaccination. Easier access to the influenza vaccination was not associated with its receipt. Conclusion: A positive patient attitude toward the influenza vaccine is associated with its use. ICD clinic practitioners may have an opportunity to explore any misconceptions toward the influenza vaccine at each clinic visit in hope of increasing its receipt. Given the importance of this vaccination, future studies are recommended.
    Canadian journal of cardiovascular nursing = Journal canadien en soins infirmiers cardio-vasculaires 09/2015; 25(3):17-23.

  • Heart rhythm: the official journal of the Heart Rhythm Society 08/2015; 12(12). DOI:10.1016/j.hrthm.2015.08.027 · 5.08 Impact Factor
  • Sheldon M Singh · Harindra C Wijeysundera ·
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    ABSTRACT: Recently, novel oral anticoagulants (NOACs) have been approved for stroke prevention in patients with atrial fibrillation (AF). Although these agents overcome some disadvantages of warfarin, they are associated with increased costs. In this review, we will provide an overview of the cost-effectiveness of NOACs for stroke prevention in AF. Our comments and conclusions are limited to studies directly comparing all available NOACs within the same framework. The available cost-effectiveness analyses suggest that NOACs are cost-effective compared to warfarin, with apixaban likely being most favorable. However, significant limitations in these models are present and should be appreciated when interpreting their results.
    Current Cardiology Reports 08/2015; 17(8):618. DOI:10.1007/s11886-015-0618-4 · 1.93 Impact Factor
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    Ravi R. Bajaj · Neil Fam · Sheldon M. Singh ·
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    ABSTRACT: We present a case of a 73-year-old patient with acute left-sided hemiparesis four months after right ventricular pacemaker insertion. Post-procedural electrocardiogram revealed a paced RBBB complex and an abnormal lead path on chest X-ray. Subsequent echocardiography and computed tomography showed left ventricular pacemaker malposition with retrograde passage to the punctured subclavian artery. We also discuss the utility of routine cardiac investigations post-insertion to identify signal lead malposition as well as management strategies once identified. Copyright © 2015 Published by Elsevier B.V. on behalf of Cardiological Society of India. All rights reserved.
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    ABSTRACT: Percutaneous left atrial appendage occlusion (LAAO) is a nonpharmacologic approach for stroke prevention in nonvalvular atrial fibrillation (NVAF). No direct comparisons to novel oral anticoagulants (OACs) exists, limiting decision making on the optimal strategy for stroke prevention in NVAF patients. Addressing this gap in knowledge is timely given the recent debate by the US Food and Drug Administration regarding the effectiveness of LAAO. To assess the cost-effectiveness of LAAO and novel OACs relative to warfarin in patients with new-onset NVAF without contraindications to OAC. A cost-utility analysis using a patient-level Markov micro-simulation decision analytic model was undertaken to determine the lifetime costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER) of LAAO and all novel OACs relative to warfarin. Effectiveness and utility data were obtained from the published literature and cost from the Ontario Drug Benefits Formulary and Case Costing Initiative. Warfarin had the lowest discounted QALY (5.13 QALYs), followed by dabigatran (5.18 QALYs), rivaroxaban and LAAO (5.21 QALYs), and apixaban (5.25 QALYs). The average discounted lifetime costs were $15 776 for warfarin, $18 280 for rivaroxaban, $19 156 for apixaban, $20 794 for dabigatran, and $21 789 for LAAO. Apixaban dominated dabigatran and LAAO and demonstrated extended dominance over rivaroxaban. The ICER for apixaban relative to warfarin was $28 167/QALY. Apixaban was preferred in 40.2% of simulations at a willingness-to-pay threshold of $50 000/QALY. Assumptions regarding clinical and methodological differences between published studies of each therapy were minimized. Apixaban is the most cost-effective therapy for stroke prevention in patients with new-onset NVAF without contraindications to OAC. Uncertainty around this conclusion exists, highlighting the need for further research. © The Author(s) 2015.
    Medical Decision Making 07/2015; DOI:10.1177/0272989X15593083 · 3.24 Impact Factor
  • Arash Aryana · Mark R Bowers · Padraig Gearoid O'Neill · Sheldon M Singh ·
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    ABSTRACT: We read with interest the manuscript by Shariff and colleagues(1) published in a recent issue of the Journal of Cardiovascular Electrophysiology. In it, the authors describe the outcomes from an analysis of 365 patients who underwent cardiac implantable electronic device (CIED) implantation using an antimicrobial pouch, and 1111 patients without the use of this product (control group). During a 28-month follow-up period, the authors identified 19 CIED infections in the control arm and none associated with the use of the antimicrobial pouch. The authors subsequently contend that the overall cost associated with management of CIED infection would be nearly balanced by the cost related to the empiric use of an antimicrobial pouch in every case. As such, they conclude that routine utilization of an antibacterial pouch as 'standard of care' would be economically justifiable. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 06/2015; DOI:10.1111/jce.12728 · 2.96 Impact Factor
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    ABSTRACT: Surgical exclusion of the left atrial appendage (LAA) can frequently yield incomplete closure. We evaluated the ischemic stroke/systemic embolization (SSE) risk in patients with atrial fibrillation (AF) and complete LAA closure (cLAA) vs incompletely surgically ligated LAA (ISLL) and LAA stump after surgical suture ligation. Seventy-two patients (CHA2DS2-VASc score 4.1 ± 1.9) underwent surgical LAA ligation in conjunction with mitral valve/AF surgery and postoperative LAA evaluation using computerized tomographic angiography. Overall, cLAA was detected in 46 of 72 patients (64%), ISLL in 17 patients (24%), and LAA stump in 9 patients (12%). The incidences of oral anticoagulation (OAC) and recurrent AF were similar among the 3 groups during 44 ± 19 months of follow-up. SSE occurred in 2% of patients with cLAA vs 24% with ISLL and 0% with LAA stump (P = .006). None of the patients with SSE were receiving OAC, and all had recurrent AF during follow-up. Additionally, patients with SSE exhibited a significantly smaller ISLL neck diameter (2.8 ± 1.0 vs 7.1 ± 2.1 mm; P = .002). The annualized SSE risk was 1.9% (entire cohort), 6.5% (ISLL patients), 14.4% (ISLL patients not receiving OAC), and 19.0% (ISLL neck diameter ≤5.0 mm) per 100 patient-years of follow-up. The latter risk was nearly 5 times greater than predicted by conventional risk-stratification schemes. Moreover, ISLL emerged as an independent predictor of SSE in univariate analyses and as the sole predictor of SSE in a multivariate analysis. In patients with AF, ISLL is a predictor of SSE, independent of conventional risk stratification schemes. Consequently, OAC should be strongly considered in this high-risk cohort. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
    Heart rhythm: the official journal of the Heart Rhythm Society 05/2015; 12(7). DOI:10.1016/j.hrthm.2015.03.028 · 5.08 Impact Factor
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    ABSTRACT: There is limited comparative data on catheter ablation of atrial fibrillation (CAAF) using the second-generation cryoballoon (CB-2) versus point-by-point radiofrequency (RF). This study examines the acute/long-term CAAF outcomes using these two strategies. In this multicenter, retrospective, non-randomized analysis, procedural/clinical outcomes of 1196 patients (76% paroxysmal AF) undergoing CAAF using CB-2 (n = 773) and open-irrigated, non-force sensing RF (n = 423) were evaluated. Pulmonary vein isolation was achieved in 98% with CB-2 and 99% with RF (p = 0.168). CB-2 was associated with shorter ablation (40±14 min vs. 66±26 min; p<0.001) and procedure times (145±49 min vs. 188±42 min; p<0.001), but greater fluoroscopic utilization (29±13 min vs. 23±14 min; p<0.001). While transient (7.6% vs. 0%; p<0.001) and persistent (1.2% vs. 0%; p = 0.026) phrenic nerve palsy occurred exclusively with CB-2, other adverse event rates were similar between CB-2 (1.6%) and RF (2.6%); p = 0.207. However, freedom from AF/atrial flutter/tachycardia at 12 months following a single procedure without antiarrhythmic therapy was greater with CB-2 (76.6%) versus RF (60.4%); p<0.001. While this difference was evident in patients with paroxysmal AF (p<0.001), it did not reach significance in those with persistent AF (p = 0.089). Additionally, CB-2 was associated with reduced long-term need for antiarrhythmic therapy (16.7% vs. 22.0%; p = 0.024) and repeat ablations (14.6% vs. 24.1%; p<0.001). In this multicenter, retrospective, non-randomized study, CAAF using CB-2 coupled with RF as occasionally required was associated with greater freedom from atrial arrhythmias at 12 months following a single procedure without antiarrhythmic therapy when compared to open-irrigated, non-force sensing RF, alone. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 04/2015; 26(8). DOI:10.1111/jce.12695 · 2.96 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) has substantial impacts on healthcare resource utilization. Our objective was to understand the pattern and predictors of cumulative healthcare costs in AF patients after incident diagnosis in an emergency department (ED). Patients discharged after a first presentation of AF to an ED in Ontario, Canada, were identified from April 1, 2005, through March 31, 2010. Per-patient cumulative healthcare costs were determined until death or March 31, 2012. Join-point analyses identified clinically relevant cost phases. Hierarchical generalized linear models with a logarithmic link and gamma distribution determined predictors of cost per phase. Our cohort was 17 980 patients. During a mean follow-up of 3.9 years, 17.1% of patients died. Three distinct cost phases were identified: 2-month post-index ED visit phase, 12-month predeath phase, and a stable/chronic phase. The mean cost per patient in the first month post-index ED visit was $1876 (95% CI $1822 to $1931), $8050 (95% CI $7666 to $8434) in the month before death, and $640 (95% CI $624 to $655) per month for the stable/chronic phase. The main cost component in the post-index phase was physician services (32% of all costs) and hospitalizations for the predeath phase (72% of all costs). The CHA2DS2-VASc clinical risk score was a strong predictor of costs (rate ratio 1.91 and 5.08 for score of 7 versus score of 0 in predeath phase and postindex phase, respectively). There are distinct phases of resource utilization in AF, with highest costs in the predeath phase. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.
    Journal of the American Heart Association 03/2015; 4(4). DOI:10.1161/JAHA.114.001684 · 4.31 Impact Factor
  • Sean A Kennedy · Sheldon M Singh ·

    Canadian Medical Association Journal 02/2015; 187(3):208. DOI:10.1503/cmaj.115-0011 · 5.96 Impact Factor
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    Sheldon M. Singh · Russell J. de Souza · Ramanan Kumareswaran ·
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    ABSTRACT: The association between influenza vaccination and implantable cardiac defibrillator (ICD) therapies during influenza season is not known and is described in this study. Understanding this association is important since reduction in ICD therapies during influenza season via use of influenza vaccination would benefit patients physically and psychologically. Patients presenting to the Sunnybrook Health Sciences Center ICD clinic between September 1st, 2011 and November 31st, 2011 were asked to complete a survey evaluating their use of the influenza vaccine. The number of patients with any ICD therapy and the total number of ICD therapies in the six months before and the three months during the 2010-2011 influenza season were determined. Poisson regression analysis was employed to assess differences in the average number of ICD therapies received during the influenza season based on vaccine status (vaccinated vs. unvaccinated). The analysis was repeated after limiting the cohort to patients with a left ventricular ejection fraction ≤35%. A total of 229 patients completed the survey, 78% of whom received the influenza vaccine. Four patients had more than one ICD shock during the study period. Electrical storm was rare (n=2). A trend toward more ICD therapies (unadjusted incident rate ratio (IRR)=3.2; P=0.07) and appropriate ICD shocks (unadjusted IRR=9.0; P=0.17) was noted for unvaccinated compared to vaccinated patients. This association persisted when analysis was limited to patients with a left ventricular ejection fraction ≤35% (all ICD therapies: unadjusted IRR=5.8; P=0.045; adjusted IRR=2.6; P=0.33). No patient who received the influenza vaccine, and had a reduced ejection fraction, received an approprite ICD shock during influenza season (unadjusted P<0.002). A trend toward more ICD therapies during influenza season was observed in patients who did not receive the influenza vaccine compared to those who did. The association was stronger in patients who received appropriate ICD shocks and in patients with left ventricular systolic dysfunction. Further work to confirm these findings is recommended.
    Journal of Arrhythmia 02/2015; 47(4). DOI:10.1016/j.joa.2014.12.006
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    ABSTRACT: Administrative database research can provide insight into the real-world effectiveness of invasive electrophysiology procedures. However, no validated algorithm to identify these procedures within administrative data currently exists. To develop and validate algorithms to identify atrial fibrillation (AF), atrial flutter (AFL), supraventricular tachycardia (SVT) catheter ablation procedures, and diagnostic electrophysiology studies (EPS) within administrative data. Algorithms consisting of physician procedural billing codes and their associated most responsible hospital diagnosis codes were used to identify potential AF, AFL, SVT catheter ablation procedures and diagnostic EPS within large administrative databases in Ontario, Canada. The potential procedures were then limited to those performed between October 1, 2011 and March 31, 2013 at a single large regional cardiac center (Sunnybrook Health Sciences Center) in Ontario, Canada. These procedures were compared with a gold-standard cohort of patients known to have undergone invasive electrophysiology procedures during the same time period at the same institution. The sensitivity, specificity, positive and negative predictive values of each algorithm was determined. Algorithms specific to each of AF, AFL, and SVT ablation were associated with a moderate sensitivity (75%-86%), high specificity (95%-98%), positive (95%-98%), and negative (99%) predictive values. The best algorithm to identify diagnostic EPS was less optimal with a sensitivity of 61% and positive predictive value of 88%. Algorithms using a combination of physician procedural billing codes and accompanying most responsible hospital diagnosis may identify catheter ablation procedures within administrative data with a high degree of accuracy. Diagnostic EPS may be identified with reduced accuracy.
    Medical Care 11/2014; Publish Ahead of Print. DOI:10.1097/MLR.0000000000000274 · 3.23 Impact Factor
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    ABSTRACT: Background: While prior work has suggested that a high-grade atrioventricular block (HAVB) in the setting of an acute coronary syndrome (ACS) is associated with in-hospital death, limited information is available on the incidence of, and death associated with, HAVB in ACS patients receiving contemporary management. Methods and results: The incidence of HAVB was determined within The Global Registry of Acute Coronary Events (GRACE). The clinical characteristics, in-hospital therapies, and outcomes were compared between patients with and without HAVB. Factors associated with death in patients with HAVB were determined. A total of 59 229 patients with ACS between 1999 and 2007 were identified; 2.9% of patients had HAVB at any point during the index hospitalization; 22.7% of whom died in hospital [adjusted odds ratio (OR) = 4.2, 95% confidence interval (CI), 3.6-4.9, P < 0.001]. The association between HAVB and in-hospital death varied with type of ACS [OR: ST-segment elevation myocardial infarction (STEMI) = 3.0; non-STEMI = 6.4; unstable angina = 8.2, P for interaction < 0.001]. High-grade atrioventricular block present at the time of presentation to hospital (vs. occurring in-hospital) and early (<12 h) percutaneous coronary intervention or fibrinolysis (vs.>12 h or no intervention) were associated with improved in-hospital survival, whereas temporary pacemaker insertion was not. Patients with HAVB surviving to discharge had similar adjusted survival at 6 months compared with those without HAVB. A reduction in the rate of, but not in-hospital mortality associated with, HAVB was noted over the study period. Conclusion: Although the incidence of HAVB is low and decreasing, this complication continues to have a high risk of in-hospital death.
    European Heart Journal 09/2014; 36(16). DOI:10.1093/eurheartj/ehu357 · 15.20 Impact Factor
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    ABSTRACT: Background Left atrial appendage occlusion devices are cost effective for stroke prophylaxis in atrial fibrillation when compared with dabigatran or warfarin. We illustrate the use of value‐of‐information analyses to quantify the degree and consequences of decisional uncertainty and to identify future research priorities. Methods and Results A microsimulation decision‐analytic model compared left atrial appendage occlusion devices to dabigatran or warfarin in atrial fibrillation. Probabilistic sensitivity analysis quantified the degree of parameter uncertainty. Expected value of perfect information analyses showed the consequences of this uncertainty. Expected value of partial perfect information analyses were done on sets of input parameters (cost, utilities, and probabilities) to identify the source of the greatest uncertainty. One‐way sensitivity analyses identified individual parameters for expected value of partial perfect information analyses. Population expected value of perfect information and expected value of partial perfect information provided an upper bound on the cost of future research. Substantial uncertainty was identified, with left atrial appendage occlusion devices being preferred in only 47% of simulations. The expected value of perfect information was $8542 per patient and $227.3 million at a population level. The expected value of partial perfect information for the set of probability parameters represented the most important source of uncertainty, at $6875. Identified in 1‐way sensitivity analyses, the expected value of partial perfect information for the odds ratio for stroke with left atrial appendage occlusion compared with warfarin was calculated at $7312 per patient or $194.5 million at a population level. Conclusion The relative efficacy of stroke reduction with left atrial appendage occlusion devices in relation to warfarin is an important source of uncertainty. Improving estimates of this parameter should be the priority for future research in this area.
    Journal of the American Heart Association 09/2014; 3(5). DOI:10.1161/JAHA.114.001031 · 4.31 Impact Factor
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    ABSTRACT: Background There is increasing interest in performing left atrial appendage (LAA) occlusion at the time of atrial fibrillation (AF) ablation procedures. However, to date there has been no description of the acute changes to the LAA immediately following pulmonary vein (PV) isolation and additional left atrium (LA) substrate modification. This study assessed changes in the size and tissue characteristics of the LAA ostium in patients undergoing PV isolation. Methods This series included 8 patients who underwent cardiovascular magnetic resonance evaluation of the LA with delayed enhancement magnetic resonance imaging and contrast enhanced 3-D magnetic resonance angiography pre-, within 48 h of, and 3 months post ablation. Two independent cardiac radiologists evaluated the ostial LAA diameters and area at each time point in addition to the presence of gadolinium enhancement. Results Compared to pre-ablation values, the respective median differences in oblique diameters and LAA area were +1.8 mm, +1.7 mm, and +0.6 cm2 immediately post ablation (all NS) and −2.7 mm, −2.3 mm, and −0.5 cm2 at 3 months (all NS). No delayed enhancement was detected in the LAA post ablation. Conclusion No significant change to LAA diameter, area, or tissue characteristics was noted after PV isolation. While these findings suggest the safety and feasibility of concomitant PV isolation and LAA device occlusion, the variability in the degree and direction of change of the LAA measurements highlights the need for further study.
    Journal of Arrhythmia 09/2014; 31(2). DOI:10.1016/j.joa.2014.08.005
  • Asaf Danon · Yair Elitzur · Krishna Kumar Mohanan Nair · Sheldon M Singh ·
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    ABSTRACT: We read with great interest the article on atrial-esophageal fistula (AEF) outcome with stenting vs. surgical repair. We commend Mohanty and colleagues for this report that helps us better understand the management of this rare but dreadful complication. This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 07/2014; 25(9). DOI:10.1111/jce.12493 · 2.96 Impact Factor
  • Asaf Danon · Krishna Kumar Mohanan Nair · Sheldon M Singh ·

    Europace 06/2014; 17(1). DOI:10.1093/europace/euu140 · 3.67 Impact Factor
  • Sean A Kennedy · Sheldon M Singh ·

    Canadian Medical Association Journal 06/2014; 186(15). DOI:10.1503/cmaj.131252 · 5.96 Impact Factor

Publication Stats

383 Citations
235.28 Total Impact Points

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  • 2014-2015
    • McMaster University
      Hamilton, Ontario, Canada
  • 2013-2015
    • Sunnybrook Health Sciences Centre
      • Department of Medicine
      Toronto, Ontario, Canada
  • 2009-2015
    • University of Toronto
      • • Faculty of Medicine
      • • Department of Medicine
      Toronto, Ontario, Canada
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2009-2011
    • Icahn School of Medicine at Mount Sinai
      • Division of Cardiology
      Manhattan, New York, United States
  • 2008-2009
    • Massachusetts General Hospital
      • Division of Cardiology
      Boston, Massachusetts, United States