Sheldon M Singh

McMaster University, Hamilton, Ontario, Canada

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Publications (55)259.57 Total impact

  • 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
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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 · 2.88 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 · 4.92 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; DOI:10.1111/jce.12695 · 2.88 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 · 2.88 Impact Factor
  • Sean A Kennedy, Sheldon M Singh
    Canadian Medical Association Journal 02/2015; 187(3):208. DOI:10.1503/cmaj.115-0011 · 5.81 Impact Factor
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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.
    Journal of Arrhythmia 02/2015; 47. 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; DOI:10.1097/MLR.0000000000000274 · 2.94 Impact Factor
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    ABSTRACT: 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.
    European Heart Journal 09/2014; 36(16). DOI:10.1093/eurheartj/ehu357 · 14.72 Impact Factor
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    ABSTRACT: 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.
    Journal of the American Heart Association 09/2014; 3(5). DOI:10.1161/JAHA.114.001031 · 2.88 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
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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 · 2.88 Impact Factor
  • Europace 06/2014; 17(1). DOI:10.1093/europace/euu140 · 3.05 Impact Factor
  • Sean A Kennedy, Sheldon M Singh
    Canadian Medical Association Journal 06/2014; 186(15). DOI:10.1503/cmaj.131252 · 5.81 Impact Factor
  • JAMA Internal Medicine 04/2014; 174(6). DOI:10.1001/jamainternmed.2014.1208 · 13.25 Impact Factor
  • The Canadian journal of cardiology 04/2014; 30(10). DOI:10.1016/j.cjca.2014.04.005 · 3.94 Impact Factor
  • Yair Elitzur, Asaf Danon, Steve K. Singh, Sheldon M. Singh
    The Canadian journal of cardiology 01/2014; · 3.94 Impact Factor
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    ABSTRACT: Atrioesophageal fistula (AEF) is an infrequent complication of radiofrequency (RF) ablation for atrial fibrillation (AF). The aim of this study was to determine the prevalence and operator-dependent factors associated with AEF using a nationwide survey of electrophysiologists (EP). Thirty-eight EPs performing AF ablation between 2008 and 2012 were invited to complete a web-based questionnaire assessing the prevalence and factors associated with AEF. Responses were obtained from 25 EPs (68 %) accounting for 7,016 AF ablations. Five cases of proven AEF (0.07 %) were reported. Operators who reported AEF [AEF (+)] more often used general anesthesia (GA) [90 % AEF (+) vs. 44 % AEF (-), p = 0.046]. AEF (+) operators were also more likely to be users of the non-brushing technique in the posterior wall of the LA [5 (100 %) AEF (+) vs. 5 (25 %) AEF (-), p = 0.005]. The combined usage of GA and non-brushing technique during LA posterior wall ablation had a strong association with AEF (+) operators [4 (80 %) AEF (+) vs. 2 (10 %) AEF (-), p = 0.002]. There was a trend towards higher maximal RF energy setting in the posterior wall [47.4 + 7.6 AEF (+) vs. 40.2 + 8 AEF (-), p = 0.09]. Other procedure parameters were similar. The reported prevalence of AEF among Canadian AF ablators is 0.07 %. AEF was associated with high mortality. The use of GA and non-brushing movements during posterior wall ablation were two factors associated with AEF.
    Journal of Interventional Cardiac Electrophysiology 12/2013; 39(2). DOI:10.1007/s10840-013-9853-z · 1.55 Impact Factor
  • Krishna Kumar Mohanan Nair, Sheldon M Singh
    Europace 10/2013; 16(7). DOI:10.1093/europace/eut308 · 3.05 Impact Factor
  • Asaf Danon, Sheldon M Singh
    The Canadian journal of cardiology 08/2013; 29(10). DOI:10.1016/j.cjca.2013.06.011 · 3.94 Impact Factor

Publication Stats

405 Citations
259.57 Total Impact Points


  • 2014–2015
    • McMaster University
      Hamilton, Ontario, Canada
  • 2003–2015
    • University of Toronto
      • • Faculty of Medicine
      • • Department of Medicine
      • • Institute of Health Policy, Management and Evaluation
      Toronto, Ontario, Canada
  • 2012–2014
    • Sunnybrook Health Sciences Centre
      • • Division of Cardiology
      • • Department of Medicine
      Toronto, Ontario, Canada
  • 2009–2011
    • Icahn School of Medicine at Mount Sinai
      • Division of Cardiology
      Manhattan, New York, United States
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2008–2009
    • Massachusetts General Hospital
      • Division of Cardiology
      Boston, Massachusetts, United States