Sheldon M Singh

Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

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Publications (47)214.2 Total impact

  • [Show abstract] [Hide abstract]
    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;
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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; · 14.72 Impact Factor
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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; · 3.48 Impact Factor
  • 06/2014;
  • The Canadian journal of cardiology 04/2014; · 3.12 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 01/2014;
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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. 01/2014; 3(5).
  • Yair Elitzur, Asaf Danon, Steve K. Singh, Sheldon M. Singh
    The Canadian journal of cardiology 01/2014; · 3.12 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; · 1.39 Impact Factor
  • Krishna Kumar Mohanan Nair, Sheldon M Singh
    Europace 10/2013; · 2.77 Impact Factor
  • Asaf Danon, Sheldon M Singh
    The Canadian journal of cardiology 08/2013; · 3.12 Impact Factor
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    ABSTRACT: The initial experience with left atrial esophageal fistula (LAEF) secondary to atrial fibrillation (AF) ablation procedures revealed a near universal mortality. A comprehensive description of the principles of LAEF repair in the modern era and its resulting impact on morbidity and mortality are lacking in the literature. To describe the presentation, surgical management and outcomes of patients with LAEF. A retrospective cohort analysis of 29 patients was performed, including previously unpublished cases of surgically repaired LAEF from 4 institutions (n=6), and all published cases of surgically repaired (n=16) or stented (n=7) LAEF. The average age was 55±13 years, 75% male, undergoing radiofrequency energy catheter ablation (n=26), cryoablation (n=1), high intensity focused ultrasound ablation (n=1) and surgical mini-MAZE (n=1), and presenting 30±12 days post ablation procedure. Overall 55% of patients receiving an intervention for LAEF died (41% surgical repair; 100% stent). Patients who did not receive primary esophageal repair were more likely to experience post-operative complications including mediastinitis, need for percutaneous endoscopic gastrostomy (PEG) feeds, esophageal stent or death (P=0.05). Additionally, interposing tissue between the repaired esophagus and LA resulted in fewer post-operative complications (P=0.02). While improved relative to initial reports, mortality associated with LAEF remains high after corrective intervention. Primary esophageal repair with the placement of tissue between the repaired esophagus and LA may result in lower morbidity and mortality.
    Heart rhythm: the official journal of the Heart Rhythm Society 08/2013; · 4.56 Impact Factor
  • Journal of Cardiovascular Electrophysiology 05/2013; · 3.48 Impact Factor
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    ABSTRACT: BACKGROUND: Percutaneous left atrial appendage (LAA) occlusion and novel pharmacological therapies are now available to manage stroke risk in patients with non-valvular atrial fibrillation (NVAF). However, the cost effectiveness of LAA occlusion compared to dabigatran and warfarin in patients with NVAF is unknown. METHODS AND RESULTS: Cost-utility analysis using a patient level Markov micro-simulation decision analytic model with a lifetime horizon was undertaken to determine the lifetime costs, quality-adjusted life years (QALY), and the incremental cost-effectiveness ratio (ICER) of LAA occlusion in relation to dabigatran and warfarin in patients with NVAF at risk for stroke without contraindications to oral anticoagulation (OAC). The analysis was performed from the perspective of the Ontario Ministry of Health and Long Term Care, the 3(rd) party payer for insured health services in Ontario, Canada. Effectiveness and utility data were obtained from the published literature. Cost data were obtained from the Ontario Drug Benefits Formulary and the Ontario Case Costing Initiative. Warfarin therapy had the lowest discounted QALY of 4.55 QALYs, followed by dabigatran at 4.64 QALYs, and LAA occlusion at 4.68 QALY. The average discounted lifetime cost for a patient on warfarin was $21 429, $25 760 for dabigatran and $27 003 for LAA occlusion. Compared with warfarin, the ICER for LAA occlusion was $41 565. Dabigatran was extendedly dominated. CONCLUSIONS: Percutaneous LAA occlusion represents a novel therapy for stroke reduction in patients at risk with NVAF that is cost-effective compared to warfarin.
    Circulation 05/2013; · 15.20 Impact Factor
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    ABSTRACT: Abstract Objectives: Data regarding efficacy and safety of three-dimensional localisation systems (3D) are limited. We performed a meta-analysis of randomized trials comparing combined fluoroscopy and 3D guided to fluoroscopically-only guided procedures. Design: A systematic search was performed using multiple databases between 1990- 2010. Outcomes were acute and long-term success, ablation, procedure and fluoroscopic times, radiation dose (RD), and complications. Results: Thirteen studies involving 1292 patients were identified. 3D were tested against fluoroscopic guidance in 666 patients for supraventricular tachycardia (SVT), atrial flutter (AFL), atrial fibrillation (AF) and ventricular tachycardia (VT). Acute and long-term freedom from arrhythmia were not significantly different between 3D and control for AFL (acute success 97% vs. 93%, p=0.57; chronic success 93% vs. 96%, p=0.90) or SVT (acute success 94% vs. 100%, p=0.36; chronic success 88% vs. 88%, p=0.80). A shorter fluoroscopic time was achieved with 3D in AFL (p<0.001) and SVT (p=0.002). RD was significantly less for both AFL (p=0.002) and SVT (p=0.01). Ablation & procedure time and complications were not statistically different. Conclusions: Success, procedure time, and complications were similar between fluoroscopic and 3D-guided ablations. Fluoroscopic time and RD were significantly reduced for ablation of AFL and SVT with 3D.
    Scandinavian cardiovascular journal: SCJ 05/2013; · 1.07 Impact Factor
  • Sheldon M Singh, Isabelle Nault
    Canadian Medical Association Journal 04/2013; · 6.47 Impact Factor
  • Hatim Al Lawati, Sheldon M Singh
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    ABSTRACT: We describe a case of post-operative inferior myocardial infarction after abdominal aortic aneurysm repair due to compromise of a gastroepiploic coronary arterial graft.
    Indian heart journal 09/2012; 64(5):530-531.
  • Journal of Cardiovascular Electrophysiology 03/2012; 23(9):1033-4. · 3.48 Impact Factor
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    ABSTRACT: Angiotensin-converting enzyme (ACE) inhibitor use in patients at high risk of coronary artery disease has been associated with a decrease in the risk of myocardial infarction (MI) and death. However, it is unclear whether chronic use of these agents modifies the course and outcome of an acute coronary syndrome (ACS). This study assessed the association between chronic use of ACE inhibitors and clinical outcomes in patients with ACS. From 1999 through 2008, 13,632 Canadian patients with ACS were identified in the Global Registry of Acute Coronary Events (GRACE), the expanded GRACE (GRACE(2)), and the Canadian Registry of Acute Coronary Events (CANRACE). Patients were stratified by previous use of an ACE inhibitor. Clinical characteristics, in-hospital treatment, and outcomes were compared between the 2 groups. Multivariable logistic regression analysis adjusting for GRACE risk score and other clinical factors was performed. Patients receiving an ACE inhibitor before the ACS had a higher prevalence of diabetes (40.6% vs 21.2%, p <0.001), previous MI (51.8% vs 23.3%, p <0.001), heart failure (18.0% vs 6.9%), and higher GRACE scores at presentation (133 vs 124, p <0.001). Multivariable analysis demonstrated no significant association between previous ACE inhibitor use and death (adjusted odds ratio [OR] 1.15, confidence interval [CI] 0.90 to 1.49, p = 0.27), in-hospital re-MI (adjusted OR 0.99, CI 0.78 to 1.25, p = 0.91), or the composite end point of death/re-MI (adjusted OR 1.01, CI 0.84 to 1.20, p = 0.94). In conclusion, previous use of an ACE inhibitor is not independently associated with improved in-hospital outcomes after an ACS.
    The American journal of cardiology 11/2011; 109(3):332-6. · 3.58 Impact Factor
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    ABSTRACT: Beyond pulmonary vein isolation (PVI), adjuvant ablation at the sites of complex fractionated atrial electrograms (CFAE) has been shown to improve the long-term success of catheter ablation of persistent atrial fibrillation (AF). However, this approach often requires extensive ablation due to the widespread distribution of CFAE within the left atrium. An optimal strategy would identify areas of CFAE which, when selectively targeted with ablation, result in AF termination with an acceptable long-term freedom from AF. It is possible that the intraprocedural administration of an antiarrhythmic drug may help accomplish this. The Modified Ablation Guided by Ibutilide Use in Chronic AF (MAGIC-AF) Study is an international multicenter prospective randomized double-blinded clinical trial assessing the utility of the intraprocedural administration of 0.25 mg of intravenous ibutilide before performing CFAE ablation. The primary efficacy endpoint of this study will be the freedom from AF at 1 year after a single procedure off antiarrhythmic agents. Safety endpoints will include procedural and radiofrequency ablation time as well as overall procedural complication rate. Patients undergoing a first ever catheter ablation procedure for persistent AF will be included. Individuals with hypertrophic cardiomyopathy, complex congenital heart disease including atrial septal defects, and ejection fraction <35% will be excluded from the study. All patients will first undergo PVI. Those patients who remain in AF will then be randomized in a 1:1 fashion to receive either 0.25 mg intravenous ibutilide or saline placebo followed by a CFAE based ablation strategy. Two hundred randomized patients will be enrolled in this study-100 in each study arm. The MAGIC-AF study will assess the utility of a combined pharmaco-ablative strategy in patients with persistent AF undergoing a CFAE based ablation strategy.
    Journal of Cardiovascular Electrophysiology 10/2011; 23(4):352-8. · 3.48 Impact Factor

Publication Stats

288 Citations
214.20 Total Impact Points


  • 2011–2014
    • Sunnybrook Health Sciences Centre
      • Division of Cardiology
      Toronto, Ontario, Canada
  • 2003–2014
    • University of Toronto
      • • Faculty of Medicine
      • • Sunnybrook Health Sciences Centre
      • • Department of Medicine
      Toronto, Ontario, Canada
  • 2010–2011
    • Icahn School of Medicine at Mount Sinai
      Manhattan, New York, United States
  • 2008
    • Massachusetts General Hospital
      • Division of Cardiology
      Boston, MA, United States