C R Kerr

University of British Columbia - Vancouver, Vancouver, British Columbia, Canada

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Publications (122)634.77 Total impact

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    ABSTRACT: Evaluation of: Barrett PM, Komatireddy R, Haaser S et al. Comparison of 24-hour Holter monitoring with 14-day novel adhesive patch electrocardiographic monitoring. Am. J. Med. 127(1), 95.e11-95.e17 (2014). The investigation of cardiac arrhythmias in the outpatient ambulatory setting has traditionally been initiated with the Holter monitor. Using the continuous recording over 24 or 48 h, the Holter monitor permits the detection of baseline rhythm, dysrhythmia and conduction abnormalities, including heart block and changes in the ST segment that may indicate myocardial ischemia. However, apart from the bulkiness and inconvenience of the device itself, the lack of extended monitoring results in a diagnostic yield of typically less than 20%. In this study by Barrett et al., 146 patients referred for the evaluation of cardiac arrhythmia were prospectively enrolled to wear both the 24-h Holter monitor and 14-day adhesive patch monitor (Zio(®) Patch) simultaneously. The primary outcome was the detection of any one of six arrhythmias: supraventricular tachycardia, atrial fibrillation/flutter, pause >3 s, atrioventricular block, ventricular tachycardia, or polymorphic ventricular tachycardia/fibrillation. The adhesive patch monitor detected more arrhythmia events compared with the Holter monitor over the total wear time (96 vs 61 events; p < 0.001), although the Holter monitor detected more events during the initial 24-h monitoring period (61 vs 52 events; p = 0.013). Novel, single-lead, intermediate-duration, user-friendly adhesive patch monitoring devices, such as the Zio Patch, represent the changing face of ambulatory ECG monitoring. However, the loss of quality, automated rhythm analysis and inability to detect myocardial ischemia continue to remain important issues that will need to be addressed prior to the implementation of these new devices.
    Future Cardiology 05/2014; 10(3):319-22.
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    ABSTRACT: This study reports the impact of cardiac resynchronization therapy (CRT) on hospitalizations in patients randomized to implantable defibrillator (ICD) or ICD-CRT in the Resynchronization-Defibrillation for Ambulatory Heart Failure Trial (RAFT). Hospitalization rates and length of hospital stay were compared between the two groups. At 18 months follow-up, the number of patients hospitalized for any cause was similar in the ICD (n=351, 38.8%) and ICD-CRT groups (n=331, 30.0%). The number of patients hospitalized for heart failure (HF) was significantly lower in the ICD-CRT (n=101, 11.3%) vs the ICD group (n=141, 15.6%, p=0.003). The number of patients hospitalized for a device-related indication was similar in the ICD-CRT group (n=147, 16.4%) vs the ICD group (n=126, 13.9%, p = 0.148). The total number of hospitalizations for any cause (n=1448 vs n=1553, p=0.042), any cardiovascular cause (n=667 vs n=790, p=0.017) and any HF cause (n=385 vs n=505, p<0.0001) was significantly lower in ICD-CRT group vs the ICD group whereas the number of hospitalizations for device-related causes was significantly higher in the ICD-CRT group vs the ICD group (246 vs 159, p<0.001) Although, the reduction in hospitalizations for HF in the CRT-ICD group was offset by an increased number of hospitalizations for device-related indications, the length of hospital stay for any cause was significantly lower in the ICD-CRT group (8.83±13.30 days) vs the ICD group (9.59±14.40 days, p=0.005) . ICD-CRT therapy significantly reduces hospitalizations and total days in hospital in patients with NYHA II/III HF compared to ICD therapy despite increased admissions for device-related indications. www.clinicaltrials.gov Identifier: NCT00251251.
    Circulation 03/2014; · 15.20 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is the most common sustained arrhythmia seen in clinical practice, and accounts for most arrhythmia-related emergency room visits and hospital admissions. The present-day management of AF is centred on improving arrhythmia-related symptoms, exercise tolerance, and quality of life, and reducing the morbidity and mortality associated with AF (ie, the prevention of stroke or systemic thromboembolism and tachycardia-induced cardiomyopathy). The contemporary management of AF is centred on the apparently competing strategies of rate and rhythm control, which are more appropriately viewed as complementary. This contemporary review will discuss the rationale underpinning the rate control strategy, and focus on practical aspects of undertaking a rate control strategy.
    The Canadian journal of cardiology 04/2013; · 3.12 Impact Factor
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    ABSTRACT: BACKGROUND: There is a relative paucity of data linking inappropriate implantable cardioverter-defibrillator (ICD) shocks to adverse clinical outcomes. OBJECTIVE: To examine the association between inappropriate ICD shocks and mortality or heart transplantation in a large population cohort. DESIGN, SETTING, PATIENTS: A cohort study which included all subjects who underwent ICD implantation between 1998 and 2008 and were followed up at our institution. MAIN OUTCOME MEASURES: Multivariable Cox regression analyses were conducted to investigate the effect of inappropriate shocks on the risk of death and heart transplantation. Appropriate and inappropriate ICD therapies were modelled as time-dependent covariates. RESULTS: A total of 1698 patients were included. During a median follow-up of 30 months, there were 246 (14.5%) deaths and 42 (2.5%) heart transplants. The incidence of inappropriate shocks was 10% at 1 year and 14% at 2 years. In the adjusted model, inappropriate shocks were not associated with death or transplantation (HR=0.97, 95% CI 0.70 to 1.36, p value=0.873). In contrast, appropriate shocks were associated with adverse outcomes (HR=3.11, 95% CI 2.41 to 4.02, p value<0.001). The lack of association between inappropriate shocks and outcomes persisted for those with severely impaired left ventricular function (ejection fraction <30%) and for those receiving multiple inappropriate treatments. CONCLUSIONS: In this study, we observed no association between inappropriate ICD shocks and increased mortality or heart transplantation, even among those with severely impaired cardiac function. These findings question whether inappropriate ICD shocks lead to adverse outcomes.
    Heart (British Cardiac Society) 03/2013; · 5.01 Impact Factor
  • Pacing and Clinical Electrophysiology 07/2012; · 1.75 Impact Factor
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    ABSTRACT: In the era of increasing implantable cardioverter defibrillator (ICD) complexity, the ICD patient alert is deemed to be an important feature in the early detection of ICD system malfunction and is either an audible or a vibratory alert. We sought to evaluate the patient's ability to detect these ICD alerts in the device clinic setting as a surrogate endpoint of clinical utility. From 1 November 2006 to 31 March 2008, 563 patients with an ICD equipped with either an audible patient alert (APA, Medtronic and Guidant; n = 485) or a vibratory monitoring alert ([VMA, St Jude Medical; n = 78) had their alarm demonstrated in the quiet clinic setting. The ability to recognize the alert was analysed and then stratified by gender, age, manufacturer, type of alert, and pocket location. The average patient age was 63.3 (± 13.6) years and 82.8% of patients were male. Implantable cardioverter defibrillator manufacturers were Medtronic (n = 464), Boston Scientific (n = 21), and SJM (n = 78). The APA was heard in 86.0% of patients. This was less likely in patients who were older, male, and where the device was placed in the submuscular position. Every patient with a VMA sensed their alert. In the current ICD alert technology, the ability to sense the ICD alert in the device clinic appears to be higher for the VMA than for the APA. In particular, older patients and male patients are less likely to sense the APA.
    Europace 11/2010; 12(11):1571-3. · 2.77 Impact Factor
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    ABSTRACT: The pharmacologic management of atrial fibrillation (AF), the most common sustained cardiac arrhythmia, has been traditionally dichotomized into control of ventricular rate or re-establishment and maintenance of sinus rhythm. The purpose of this study was to evaluate the use of rate-controlling drugs and antiarrhythmic drugs (AAD) in the Canadian Registry of Atrial Fibrillation (CARAF) over a 16-year period from 1991 through 2007. 1,400 patients with new-onset paroxysmal AF who were enrolled in CARAF were included in this analysis. We assessed trends in ventricular rate-controlling medication use (digoxin, beta-blockers, and calcium channel blockers) and AAD (class IA, IC, and III antiarrhythmic agents) at baseline and follow-up visits as well as by calendar year. AAD use increased initially from 1991 to 1994 (peak use 42.5%) before steadily declining. Sotalol use decreased (27% to 6%), whereas amiodarone use increased (1.6% to 17.9%). Rate-controlling medication use decreased from 1991 to 1995 (54.1% to 34.1%) due to declining digoxin use (62.9% to 16.3%). After 1999, there was a continued increase in rate-controlling medication use (peak use 52.5% in 2007) due to increased beta-blocker use (17% to 45.7%). Calcium channel blockers use changed little over the duration of the study. The management of AF has undergone significant shifts since 1990, reflecting the influence of drug development, prevailing belief systems, the impact of large clinical trials, and evidence-based recommendations. Monitoring of pharmacotherapy trends will provide insight into the real-world application of evidence-based guidelines as well as allow the opportunity to identify deficiencies and improve patient care.
    Heart rhythm: the official journal of the Heart Rhythm Society 09/2010; 7(9):1171-7. · 4.56 Impact Factor
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    ABSTRACT: There is uncertainty about the proper role of defibrillation testing (DT) at the time of implantable cardioverter defibrillator (ICD) insertion. A prospective registry was conducted at 13 sites in Canada between January 2006 and October 2007. To document the details of DT, the reasons for not conducting DT, and the costs and complications associated with DT. DT was conducted at implantation in 230 of 361 patients (64%). DT was more likely to be conducted for new implants compared with impulse generator replacements (71% vs 32%, P = 0.0001), but was similar for primary and secondary prevention indications (64% vs 63%, P = NS). Among patients not having DT, the reason(s) given were: considered unnecessary (44%); considered unsafe, mainly due to persistent atrial fibrillation (37%); lack of an anesthetist (20%); and, patient or physician preference (6%). When performed, DT consisted of a single successful shock > or = 10J below maximum device output in 65% of cases. A 10J safety-margin was met by 97% of patients, requiring system modification in 2.3%. Major perioperative complications occurred in 4.4% of patients having DT versus 6.6% of patients not having DT (P = NS). ICD insertion was $844 more expensive for patients having DT (P = 0.16), largely due to increased costs ($28,017 vs $24,545) among patients having impulse generator replacement (P = 0.02). DT was not performed in a third of ICD implants, usually due to a perceived lack of need or relative contraindication.
    Journal of Cardiovascular Electrophysiology 10/2009; 21(2):177-82. · 3.48 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is commonly associated with impaired quality of life. There is no simple validated scale to quantify the functional illness burden of AF. The Canadian Cardiovascular Society Severity in Atrial Fibrillation (CCS-SAF) scale is a bedside scale that ranges from class 0 to 4, from no effect on functional quality of life to a severe effect on life quality. This study was performed to validate the scale. In 484 patients with documented AF (62.2+/-12.5 years of age, 67% men; 62% paroxysmal and 38% persistent/permanent), the SAF class was assessed and 2 validated quality-of-life questionnaires were administered: the SF-36 generic scale and the disease-specific AFSS (University of Toronto Atrial Fibrillation Severity Scale). There is a significant linear graded correlation between the SAF class and measures of symptom severity, physical and emotional components of quality of life, general well-being, and health care consumption related to AF. Patients with SAF class 0 had age- and sex-standardized SF-36 scores of 0.15+/-0.16 and -0.04+/-0.31 (SD units), that is, units away from the mean population score for the mental and physical summary scores, respectively. For each unit increase in SAF class, there is a 0.36 and 0.40 SD unit decrease in the SF-36 score for the physical and mental components. As the SAF class increases from 0 to 4, the symptom severity score (range, 0 to 35) increases from 4.2+/-5.0 to 18.4+/-7.8 (P<0.0001). The CCS-SAF scale is a simple semiquantitative scale that closely approximates patient-reported subjective measures of quality of life in AF and may be practical for clinical use.
    Circulation Arrhythmia and Electrophysiology 06/2009; 2(3):218-24. · 5.95 Impact Factor
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    ABSTRACT: The National Heart, Lung, and Blood Institute convened an expert panel April 28 to 29, 2008, to identify gaps and recommend research strategies to prevent atrial fibrillation (AF). The panel reviewed the existing basic scientific, epidemiological, and clinical literature about AF and identified opportunities to advance AF prevention research. After discussion, the panel proposed the following recommendations: (1) enhance understanding of the epidemiology of AF in the population by systematically and longitudinally investigating symptomatic and asymptomatic AF in cohort studies; (2) improve detection of AF by evaluating the ability of existing and emerging methods and technologies to detect AF; (3) improve noninvasive modalities for identifying key components of cardiovascular remodeling that promote AF, including genetic, fibrotic, autonomic, structural, and electrical remodeling markers; (4) develop additional animal models reflective of the pathophysiology of human AF; (5) conduct secondary analyses of already-completed clinical trials to enhance knowledge of potentially effective methods to prevent AF and routinely include AF as an outcome in ongoing and future cardiovascular studies; and (6) conduct clinical studies focused on secondary prevention of AF recurrence, which would inform future primary prevention investigations.
    Circulation 03/2009; 119(4):606-18. · 15.20 Impact Factor
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    ABSTRACT: Radiofrequency ablation (RFA) has become an accepted therapy for atrial fibrillation (AF). The objective of this study was to perform an economic evaluation of RFA versus antiarrhythmic drug therapy (AAD) as first-line treatment of symptomatic paroxysmal AF. To estimate and compare the costs of RFA versus AAD, a decision analytic model was developed using data on AF recurrence, hospitalization rates, AAD use, and treatment crossover rates derived directly from the Randomized Trial of RFA versus AAD as First-Line Treatment of Symptomatic Atrial Fibrillation (RAAFT). Resource utilization was modeled to reflect Canadian clinical practice in AF management. Unit costs of healthcare interactions were based on available Canadian government resources and published literature. Costs were assessed based on intention-to-treat. Total expected costs were computed to include initial treatment, hospital stay, physician fees, diagnostic tests, and outpatient visits. Sensitivity analyses were performed to account for the uncertainties. The study was conducted from the third party payer's perspective and costs are reported in 2005 Canadian dollars with 3% discount rate used in the analysis. During the 2-month blanking period following therapy selection, total average costs for RFA and AAD were $10,465 and $2,556, respectively; at 1-year follow-up, these were $12,823 and $6,053; and total 2-year cumulative total average costs were $15,303 and $14,392. Sensitivity analyses did not alter the results, suggesting the model is robust. RFA as first-line treatment strategy in patients with symptomatic paroxysmal AF was cost neutral 2 years after the initial procedure compared to AAD.
    Journal of Cardiovascular Electrophysiology 10/2008; 20(1):7-12. · 3.48 Impact Factor
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    ABSTRACT: Transcatheter aortic valve replacement (AVR) is a promising approach to aortic valve disease. The implications of this new therapy are not entirely known. We describe the potential for the development of new atrioventricular (AV) block. Atrioventricular block is a known complication of conventional surgical AVR. Block is presumed to occur as a consequence of surgical trauma to the cardiac conduction tissue during excision of the diseased aortic valve and débridement of the calcified annulus. Whether AV block might occur as a consequence of nonsurgical implantation of an aortic stent valve is unknown. We reviewed our experience with patients undergoing transcatheter AVR using both the percutaneous transarterial and the open-chest direct left ventricular apical ventriculotomy approaches. Patients were considered at high risk for conventional surgery because of comorbidities. Continuous arrhythmia monitoring was performed for at least 48 h after the valve implantation procedure. Patients who developed apparently new, clinically significant AV block were identified. Transcatheter AVR was successfully performed in 123 patients. Seventeen of these patients (13.8%) had pre-existing permanent pacemakers. Two patients (1.6%) required pacemaker implantation because of pre-existing intermittent bradycardia. Seven patients (5.7%) developed new and sustained complete AV block requiring pacemaker implantation. An additional 4 patients (3.3%) developed new and sustained left bundle branch block but did not require pacemaker implantation. As with conventional AVR surgery, transcatheter AVR may result in impaired atrioventricular conduction. Physicians and patients should be aware of the potential for AV block and pacemaker dependence.
    JACC. Cardiovascular Interventions 07/2008; 1(3):305-9. · 1.07 Impact Factor
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    ABSTRACT: Statins have important pleiotropic effects and have been shown to reduce vascular inflammation and the incidence of atrial fibrillation (AF) after cardiac surgery. The role of statins in patients with existing AF is poorly understood. We examined the effect of statins on recurrence of AF in patients after successful cardioversion. Statin use and documented recurrence of AF after successful cardioversion were evaluated in 625 patients with new onset AF who were followed prospectively in the Canadian Registry of Atrial Fibrillation. Logistic regression was used to model the effect of statin use on the recurrence of AF at 1 year while adjusting for potential confounders including concurrent medications. In a predominantly male population (62%) with median age 63 years, 12.3% were on statins at baseline. Overall, 32.5% had documented recurrence of AF at 1 year; 23.4% in patients on statins compared to 33.8% in those not on statins (P = .07). After adjustment for baseline differences and concomitant beta-blocker use, statin use was associated with a 74% reduction in AF recurrence, but only in statin users on beta-blockers (OR 0.26, 95% CI 0.10-0.66); statin users not on beta-blockers (OR 1.07, 95% CI 0.44-2.58). In an observational study of patients with new onset AF, statin use was associated with a significant 74% reduction in the odds of recurrent AF, but only in patients also taking beta-blockers. Importantly, statin without concomitant beta-blocker use was not associated with any changes in AF recurrence.
    American heart journal 12/2007; 154(5):908-13. · 4.65 Impact Factor
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    ABSTRACT: Introduction: There is emerging evidence for clinical superiority of catheter ablation over rate and rhythm control strategies in paroxysmal atrial fibrillation (PAF). The objective of this study was to compare costs related to medical therapy versus catheter ablation for PAF in Ontario (Canada).Methods: Costs related to medical therapy in the analysis included the cost of anticoagulation, rate and rhythm control medications, noninvasive testing, physician follow-up visits, and hospital admissions, as well as the cost of complications related to this management strategy. Costs related to catheter ablation were assumed to include the cost of the ablation tools (electroanatomic mapping or intracardiac echocardiography-guided pulmonary vein ablation), hospital and physician billings, and costs related to periprocedural medical care and complications. Costs related to these various elements were obtained from the Canadian Registry of Atrial Fibrillation (CARAF), government fee schedules, and published data. Sensitivity analyses looking at a range of initial success rates (50–75%) and late attrition rates (1–5%), prevalence of congestive heart failure (CHF) (20–60%), as well as discounting varying from 3% to 5% per year were performed.Results: The cost of catheter ablation ranged from $16,278 to $21,294, with an annual cost of $1,597 to $2,132. The annual cost of medical therapy ranged from $4,176 to $5,060. Costs of ongoing medical therapy and catheter ablation for PAF equalized at 3.2–8.4 years of follow-up.Conclusion: Catheter ablation is a fiscally sensible alternative to medical therapy in PAF with cost equivalence after 4 years.
    Journal of Cardiovascular Electrophysiology 08/2007; 18(9):907 - 913. · 3.48 Impact Factor
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    ABSTRACT: Although several randomized trials have detected no reduction in major cardiovascular events with the routine use of dual-chamber as opposed to ventricular pacemakers, many individuals continue to advocate their use as a means of improving exercise capacity. The Canadian Trial of Physiological Pacing (CTOPP) trial is the largest trial comparing ventricular pacing to atrial-based pacing (atrial or dual-chamber) in patients with bradycardia. All patients in this trial were asked to complete a 6-minute hall walk test (6MWT) at the time of their first study follow-up. The distance walked in 6 minutes and the patient's heart rate before and immediately after the walk were recorded. Of the 2568 patients in the CTOPP, 76% completed the 6MWT. The mean distance walked was 350 +/- 127 m in the ventricular pacing group and 356 +/- 127 m in the atrial-based group (P = NS). Similarly, there was no difference in the change in heart rate between the two groups (17 +/- 13 vs. 18 +/- 12 bpm: P = NS). However, among patients with an unpaced heart rate of </=60 bpm, patients assigned to atrial-based pacing walked farther than those randomized to ventricular pacing (361 +/- 127 vs. 343 +/- 121 m; P = .04). This was not associated with a difference in heart rate. The use of rate-adaptive pacing, irrespective of the pacing mode, resulted in a greater increase in heart rate with the 6MWT but no increase in the total distance walked. The routine use of atrial-based pacemakers, instead of ventricular pacemakers, does not improve exercise capacity, as measured by the 6MWT. However, patients with an unpaced heart rate of </=60 bpm may achieve a modest increase in their exercise capacity with atrial-based pacing.
    Heart Rhythm 08/2007; 4(8):1024-8. · 5.05 Impact Factor
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    Heart Lung and Circulation - HEART LUNG CIRC. 01/2007; 16.
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    ABSTRACT: Azimilide hydrochloride (azimilide), an investigational antiarrhythmic drug, has shown variable efficacy in preventing atrial fibrillation (AF). This study was designed to assess its efficacy in maintaining sinus rhythm in patients with paroxysmal AF and heart disease. Patients with symptomatic paroxysmal AF were screened for 1 month by transtelephonic monitoring. After recording 1 episode of AF in the screening period, they were randomized to receive azimilide 125 mg or placebo once daily. Patients were stratified by the presence or absence of congestive heart failure or coronary heart disease (CHF/CHD). A maximum of 220 patients without CHF/CHD were randomized, with the remainder having CHF/CHD. Patients with CHF/CHD were monitored for 3 days during loading. The primary efficacy analysis was the time to the first symptomatic recurrence of AF in the CHF/CHD group. Secondary analyses were the time to the first recurrence in the entire population and the time to the first recurrence in those with significant structural heart disease. The median time to recurrence of AF in the CHF/CHD group was 10 days in the 2 treatment arms. Nonsignificant trends were seen toward efficacy of azimilide in the CHF/CHD group (hazard ratio 1.28, 95% confidence interval 0.97 to 1.70, p=0.087), structural heart disease group (hazard ratio 1.22, 95% confidence interval 0.96 to 1.56, p=0.11), and overall group (hazard ratio 1.22, 95% confidence interval 1.00 to 1.49, p=0.053). No patient died. In conclusion, azimilide showed a nonsignificant trend toward efficacy in maintaining sinus rhythm in patients with AF.
    The American Journal of Cardiology 08/2006; 98(2):215-8. · 3.21 Impact Factor
  • CHARLES R. KERR, DAVID C. CHUNG, JOCELYN COOPER
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    ABSTRACT: Transesophageal pacing and recording are valuable techniques in the diagnosis and treatment of patients with arrhythmias. Bipolar pacing with bipolar catheters has been effective, but recording from the same electrodes is not possible during and immediately following pacing. We utilized a fine no. 4 French quadripolar catheter in 21 subjects to stimulate the atrium and record atrial electrical activity simultaneously. Pacing characteristics were equivalent to previously used bipolar catheters and recording was markedly enhanced. Bipolar atrial electrograms could be recorded either during pacing or at the first atrial depolarization following pacing in all patients. Thus, this quadripolar pacing lead improves the diagnostic value of studies involving transesophageal atrial pacing and recording.
    Pacing and Clinical Electrophysiology 06/2006; 9(5):644 - 651. · 1.75 Impact Factor
  • CHARLES R. KERR
    Pacing and Clinical Electrophysiology 06/2006; 17(7):1203 - 1207. · 1.75 Impact Factor
  • ANNE M. GILLIS, CHARLES R. KERR
    Pacing and Clinical Electrophysiology 06/2006; 23(8):1193 - 1196. · 1.75 Impact Factor

Publication Stats

2k Citations
634.77 Total Impact Points

Institutions

  • 1983–2013
    • University of British Columbia - Vancouver
      • • Division of Cardiology
      • • Department of Medicine
      • • Faculty of Pharmaceutical Sciences
      Vancouver, British Columbia, Canada
  • 1996–2010
    • St. Paul's Hospital
      Saskatoon, Saskatchewan, Canada
  • 2009
    • Karl Jaspers Society of North America
      United States
    • McMaster University
      Hamilton, Ontario, Canada
  • 2003–2009
    • University of Toronto
      • • Division of Cardiology
      • • Department of Medicine
      Toronto, Ontario, Canada
    • The University of Calgary
      Calgary, Alberta, Canada
  • 2007
    • Queen's University
      Kingston, Ontario, Canada
  • 2001
    • University of Ottawa
      • Department of Medicine
      Ottawa, Ontario, Canada
  • 2000
    • Abbott Northwestern Hospital
      Minneapolis, Minnesota, United States
  • 1988
    • Columbia University
      • Division of Cardiology
      New York City, NY, United States
  • 1987
    • University of Vienna
      Wien, Vienna, Austria
  • 1985
    • Vancouver General Hospital
      Vancouver, British Columbia, Canada