Publications by authors named "Martin S Green"

82 Publications

Prevalence of Left Atrial Appendage Thrombus in Patients Anticoagulated With Direct Oral Anticoagulants: Systematic Review and Meta-analysis.

CJC Open 2021 May 24;3(5):658-665. Epub 2020 Dec 24.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.

Background: Multiple studies have examined the prevalence of left atrial appendage thrombus (LAAT) in patients anticoagulated with direct oral anticoagulants (DOACs) and have reported conflicting results.

Methods: Studies reporting the prevalence of LAAT on transesophageal echocardiography (TEE) after 3 or more weeks of DOAC therapy were identified. The proportions of anticoagulated patients diagnosed with LAAT were pooled using random-effects models. Prespecified subgroup analyses by the indication of TEE (pre-atrial fibrillation [AF] ablation vs cardioversion) and TEE strategy (routine use vs selective) were conducted via stratification.

Results: Forty studies were identified: 22 full manuscripts and 18 abstracts. Only 11 studies performed TEE routinely. Most studies included patients with paroxysmal AF and low thromboembolic risk. The pooled prevalence of LAAT was 2.5% (95% confidence interval [1.6%-3.4%]). The prevalence of LAAT is lower in the pre-AF ablation group compared with pre-cardioversion (1.1% vs 4.0%,  = 0.033). Routine TEE strategy yielded a lower LAAT prevalence in both groups (0.1% vs 2.3%,  = 0.002 and 3.2% vs 5.8%,  = 0.432, respectively).

Conclusion: The reported prevalence of LAAT on TEE in patients treated with DOACs is highly variable. Factors associated with a high LAAT prevalence were pre-cardioversion indication and selective TEE strategy. Routine use of TEE before AF ablation may not be warranted.
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http://dx.doi.org/10.1016/j.cjco.2020.12.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8134939PMC
May 2021

Variant Reinterpretation in Survivors of Cardiac Arrest With Preserved Ejection Fraction (the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry) by Clinicians and Clinical Commercial Laboratories.

Circ Genom Precis Med 2021 Jun 7;14(3):e003235. Epub 2021 May 7.

Division of Cardiology, Department of Medicine (B.D., K.B., A.D.K., Z.W.M.L.), The University of British Columbia, Vancouver, Canada.

Background: Following an unexplained cardiac arrest, clinical genetic testing is increasingly becoming standard of care. Periodic review of variant classification is required, as reinterpretation can change the diagnosis, prognosis, and management of patients and their relatives.

Methods: This study aimed to develop and validate a standardized algorithm to facilitate clinical application of the 2015 American College of Medical Genetics and Association for Molecular Pathology guidelines for the interpretation of genetic variants. The algorithm was applied to genetic results in the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry, to assess the rate of variant reclassification over time. Variant classifications were then compared with the classifications of 2 commercial laboratories to determine the rate and identify sources of variant interpretation discordance.

Results: Thirty-one percent of participants (40 of 131) had at least 1 genetic variant with a clinically significant reclassification over time. Variants of uncertain significance were more likely to be downgraded (73%) to benign than upgraded to pathogenic (27%; =0.03). For the second part of the study, 50% (70 of 139) of variants had discrepant interpretations (excluding benign variants), provided by at least 1 team.

Conclusions: Periodic review of genetic variant classification is a key component of follow-up care given rapidly changing information in the field. There is potential for clinical care gaps with discrepant variant interpretations, based on the interpretation and application of current guidelines. The development of gene- and disease-specific guidelines and algorithms may provide an opportunity to further standardize variant interpretation reporting in the future. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00292032.
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http://dx.doi.org/10.1161/CIRCGEN.120.003235DOI Listing
June 2021

Defining idiopathic ventricular fibrillation: A systematic review of diagnostic testing yield in apparently unexplained cardiac arrest.

Heart Rhythm 2021 Mar 26. Epub 2021 Mar 26.

Center for Cardiovascular Innovation, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address:

Background: Idiopathic ventricular fibrillation (IVF) is diagnosed in patients with apparently unexplained cardiac arrest (UCA) after varying degrees of evaluation. This is largely due to the lack of a standardized approach to UCA.

Objective: We sought to develop an evidence-based diagnostic algorithm for IVF by systematically examining the yield of diagnostic testing in UCA probands.

Methods: Studies reporting the yield of diagnostic testing in UCA were identified in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and conference abstracts. Their methodological quality was assessed by the National Institutes of Health quality assessment tool. Meta-analyses were performed using the random effects model.

Results: A total of 21 studies were included. The pooled comprehensive diagnostic testing yield was 43% (95% confidence interval 39%-48%). A lower yield was seen when only definite diagnoses based on the prespecified criteria were used (32% vs 47%; P = .15). Epinephrine challenge, Holter monitoring, and family screening were associated with low yield (<5%), whereas cardiac magnetic resonance imaging, exercise treadmill test, and sodium-channel blocker challenge were associated with high yield (≥5%). Coronary spasm provocation, electrophysiology study, and systematic genetic testing were reported to be abnormal in a high proportion of UCA probands (>10%).

Conclusion: We developed a stepwise algorithm for UCA evaluation and criteria to assess the strength of IVF diagnosis on the basis of the diagnostic yield of UCA testing.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.030DOI Listing
March 2021

High-power, short-duration atrial fibrillation ablation compared with a conventional approach: Outcomes and reconnection patterns.

J Cardiovasc Electrophysiol 2021 May 29;32(5):1219-1228. Epub 2021 Mar 29.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Canada.

Background: The effectiveness, safety, and pulmonary vein (PV) reconnection patterns of point-by-point high-power, short-duration (HPSD) ablation relative to conventional force-time integral (FTI)-guided strategies for atrial fibrillation (AF) ablation are unknown.

Objectives: To compare 1-year freedom from atrial arrhythmia (AA), complication rates, procedural times, and PV reconnection patterns with HPSD AF AF ablation versus an FTI-guided low-power, long-duration (LPLD) strategy.

Methods: We compared consecutive patients undergoing a first ablation procedure for paroxysmal or persistent AF. The HPSD protocol utilized a power of 50 W and durations of 6-8 s posteriorly and 8-10 s anteriorly. The LPLD protocol was FTI-guided with a power of ≤25 W posteriorly (FTI ≥ 300g·s) and ≤35 W anteriorly (FTI ≥ 400g·s).

Results: In total, 214 patients were prospectively included (107 HPSD, 107 LPLD). Freedom from AA at 1 year was achieved in 79% in the HPSD group versus 73% in the LPLD group (p = .339; adjusted hazard ratio with HPSD, 0.67; 95% confidence interval, 0.36-1.23; p < .004 for non-inferiority). Procedure duration was shorter in the HPSD group (229 ± 60 vs. 309 ± 77 min; p < .005). Patients undergoing repeat ablation had a higher propensity for reconnection at the right PV carina in the HPSD group compared with the LPLD group (14/30 = 46.7% vs. 7/34 = 20.6%; p = .035). There were no differences in complication rates.

Conclusion: HPSD AF ablation resulted in similar freedom from AAs at 1 year, shorter procedure times, and a similar safety profile when compared with an LPLD ablation strategy. Patients undergoing HPSD ablation required more applications at the right carina to achieve isolation, and had a significantly higher rate of right carinal reconnections at redo procedures.
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http://dx.doi.org/10.1111/jce.14989DOI Listing
May 2021

The Hearts in Rhythm Organization: A Canadian National Cardiogenetics Network.

CJC Open 2020 Nov 29;2(6):652-662. Epub 2020 May 29.

Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.

Background: The Hearts in Rhythm Organization (HiRO) is a team of Canadian inherited heart rhythm and cardiomyopathy experts, genetic counsellors, nurses, researchers, patients, and families dedicated to the detection of inherited arrhythmias and cardiomyopathies, provision of best therapies, and protection from the tragedy of sudden cardiac arrest.

Methods: Recently, existing disease-specific registries were merged into the expanded National HiRO Registry, creating a single common data set for patients and families with inherited conditions that put them at risk for sudden death in Canada. Eligible patients are invited to participate in the registry and optional biobank from 20 specialized cardiogenetics clinics across Canada.

Results: Currently, there are 4700 participants enrolled in the National HiRO Registry, with an average of 593 participants enrolled annually over the past 5 years. The capacity to enable knowledge translation of research findings is built into HiRO's organizational infrastructure, with 3 additional working groups (HiRO Clinical Care Committee, HiRO Active Communities Committee, and HiRO Annual Symposium Committee), supporting the organization's current goals and priorities as set alongside patient partners.

Conclusion: The National HiRO Registry aims to be an integrated research platform to which researchers can pose novel research questions leading to a better understanding, detection, and clinical care of those living with inherited heart rhythm and cardiomyopathy conditions and ultimately to prevent sudden cardiac death.
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http://dx.doi.org/10.1016/j.cjco.2020.05.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7710951PMC
November 2020

Premature atrial contraction during a wide complex tachycardia: What is the mechanism?

Pacing Clin Electrophysiol 2020 11 1;43(11):1390-1392. Epub 2020 Oct 1.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Canada.

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http://dx.doi.org/10.1111/pace.14079DOI Listing
November 2020

The Clinical Utility of Continuous QT Interval Monitoring in Patients Admitted With COVID-19 Compared With Standard of Care: A Prospective Cohort Study.

CJC Open 2020 Nov 22;2(6):592-598. Epub 2020 Jul 22.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.

Background: QT interval monitoring has gained much interest during the COVID-19 pandemic because of the use of QT-prolonging medications and the concern about viral transmission with serial electrocardiograms (ECGs). We hypothesized that continuous telemetry-based QT monitoring is associated with better detection of prolonged QT episodes.

Methods: We introduced continuous cardiac telemetry (CCT) with an algorithm for automated QT interval monitoring to our designated COVID-19 units. The daily maximum automated heart rate-corrected QT (Auto-QTc) measurements were recorded. We compared the proportion of marked QTc prolongation (Long-QTc) episodes, defined as QTc ≥ 500 ms, in patients with suspected or confirmed COVID-19 who were admitted before and after CCT was implemented (control group vs CCT group, respectively). Manual QTc measurement by electrophysiologists was used to verify Auto-QTc. Charts were reviewed to describe the clinical response to Long-QTc episodes.

Results: We included 33 consecutive patients (total of 451 monitoring days). Long-QTc episodes were detected more frequently in the CCT group (69/206 [34%] vs 26/245 [11%]; < 0.0001) and ECGs were performed less frequently (32/206 [16%] vs 78/245 [32%]; < 0.0001). Auto-QTc correlated well with QTc measurement by electrophysiologists with an excellent agreement in detecting Long-QTc (κ = 0.8; < 0.008). Only 28% of patients with Long-QTc episodes were treated with recommended therapies. There was 1 episode of torsade de pointes in the control group and none in the CCT group.

Conclusions: Continuous QT interval monitoring is superior to standard of care in detecting episodes of Long-QTc with minimal need for ECGs. The clinical response to Long-QTc episodes is suboptimal.
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http://dx.doi.org/10.1016/j.cjco.2020.07.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374138PMC
November 2020

An International Multicenter Evaluation of Inheritance Patterns, Arrhythmic Risks, and Underlying Mechanisms of -Catecholaminergic Polymorphic Ventricular Tachycardia.

Circulation 2020 Sep 22;142(10):932-947. Epub 2020 Jul 22.

Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada (K.N., J.W., A.S.T., A.C.S., J.M., J.D.R.).

Background: Genetic variants in calsequestrin-2 () cause an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia (CPVT), although isolated reports have identified arrhythmic phenotypes among heterozygotes. Improved insight into the inheritance patterns, arrhythmic risks, and molecular mechanisms of -CPVT was sought through an international multicenter collaboration.

Methods: Genotype-phenotype segregation in -CPVT families was assessed, and the impact of genotype on arrhythmic risk was evaluated using Cox regression models. Putative dominant missense variants and the established recessive CASQ2-p.R33Q variant were evaluated using oligomerization assays and their locations mapped to a recent CASQ2 filament structure.

Results: A total of 112 individuals, including 36 CPVT probands (24 homozygotes/compound heterozygotes and 12 heterozygotes) and 76 family members possessing at least 1 presumed pathogenic variant, were identified. Among homozygotes and compound heterozygotes, clinical penetrance was 97.1% and 26 of 34 (76.5%) individuals had experienced a potentially fatal arrhythmic event with a median age of onset of 7 years (95% CI, 6-11). Fifty-one of 66 heterozygous family members had undergone clinical evaluation, and 17 of 51 (33.3%) met diagnostic criteria for CPVT. Relative to heterozygotes, homozygote/compound heterozygote genotype status in probands was associated with a 3.2-fold (95% CI, 1.3-8.0; =0.013) increased hazard of a composite of cardiac syncope, aborted cardiac arrest, and sudden cardiac death, but a 38.8-fold (95% CI, 5.6-269.1; <0.001) increased hazard in genotype-positive family members. In vitro turbidity assays revealed that p.R33Q and all 6 candidate dominant missense variants evaluated exhibited filamentation defects, but only p.R33Q convincingly failed to dimerize. Structural analysis revealed that 3 of these 6 putative dominant negative missense variants localized to an electronegative pocket considered critical for back-to-back binding of dimers.

Conclusions: This international multicenter study of -CPVT redefines its heritability and confirms that pathogenic heterozygous variants may manifest with a CPVT phenotype, indicating a need to clinically screen these individuals. A dominant mode of inheritance appears intrinsic to certain missense variants because of their location and function within the CASQ2 filament structure.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.045723DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7484339PMC
September 2020

The Wenckebach Phenomenon.

Curr Cardiol Rev 2021 ;17(1):10-16

University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario, K1Y 4W7, Canada.

Medicine has many great pioneers, and in 1899, one such pioneer - Karel Frederik Wenckebach made a discovery which, even to this day, remains one of the fundamental concepts within electrophysiology. Since the Wenckebach Phenomenon was first described, the field of electrophysiology has developed at a rapid pace, allowing us to observe this behaviour, and its complexities, in many new ways. In a similar way, this chapter will illustrate Wenckebach behaviour across a spectrum of modalities from the 12 lead ECG, through to the intra-cardiac recordings from both electrophysiological studies and implantable cardiac devices. In doing so, we continue to shed light on the phenomenon first identified through Wenckebach's meticulous attention to detail some 120 years ago.
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http://dx.doi.org/10.2174/1573403X16666200719022142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8142363PMC
April 2021

A Systematic Review of the Risk of Motor Vehicle Collision in Patients With Syncope.

Can J Cardiol 2021 01 14;37(1):151-161. Epub 2020 Feb 14.

Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.

Background: Drivers at risk of sudden incapacitation from syncope pose a potential threat to themselves and to society. The purpose of this systematic review is to synthesize the risk of motor vehicle collisions (MVCs) for patients with a history of syncope.

Methods: We systematically searched Medline (1946-2019) as well as Cinahl, Embase, Psychinfo, and the Transportation Research Information Documentation (1806-2017) for articles on MVCs and drivers with vasovagal syncope (VVS), arrhythmic syncope, or syncope not yet diagnosed (NYD). Quality ratings were assigned by team consensus.

Results: Eleven studies of moderate quality were included (n = 42,972). Compared with the general populations of Canada, the United States, and the United Kingdom (0.49%-2.29% per driver-year), the prospective MVC risk was lower for VVS (0.0%-0.31% per driver-year; 3 studies; n = 782) and higher for arrhythmic syncope (1.9%-3.4% per driver-year; 2 studies; n = 730). The results were more variable for syncope NYD (0.0%-6.9% per driver-year prospectively; 6 studies; n = 41,460). Patients with syncope NYD had an almost 2-fold increased MVC risk in the largest study, although the smaller studies showed contradictory findings.

Conclusions: VVS patients appear to be at very low risk for MVCs, supporting current guidelines which do not recommend driving suspension for these patients in most cases. Although the data for other forms of syncope are too limited for definitive conclusions and must be improved, arrhythmic syncope appears to be associated with nontrivial risk.
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http://dx.doi.org/10.1016/j.cjca.2020.02.070DOI Listing
January 2021

Rate Control Management of Atrial Fibrillation With Rapid Ventricular Response in the Emergency Department.

Can J Cardiol 2020 04 9;36(4):509-517. Epub 2019 Sep 9.

Department of Emergency Medicine, University of Ottawa, Ottawa, Ontario, Canada; Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada. Electronic address:

Background: There exists limited evidence on managing atrial fibrillation (AF) with rapid ventricular response in the emergency department. We sought to better understand the burden of disease in patients with AF for whom rhythm control was not successful or not attempted and identify opportunities for improved care.

Methods: We conducted a health records review of consecutive visits of patients with AF at 2 academic emergency departments. We included patients ≥ 18 years with AF, heart rate ≥ 100 beats per minute (bpm), and who were not successfully cardioverted or not attempted cardioversion. Outcomes were: (1) incidence given rate control, (2) management practices, (3) adverse events, (4) compliance with guidelines, and (5) outcomes. We performed descriptive statistics.

Results: We included 665 visits, with mean age ± standard deviation 77.4 ± 12.9, female 51.6%, mean ± standard deviation heart rate 121.6 ± 17.4 bpm, AF status (permanent 53.4%; paroxysmal 29.5%; persistent 17.1%), admitted 61.4%. Of all cases, 147 (22.1%) had primary AF and 518 (77.9%) had a rapid rate secondary to a medical cause (heart failure 12.8%; pneumonia 11.7%; sepsis 8.4%). In 117 with primary AF given rate control, 59.0% had a final rate ≤ 100 bpm and 7.7% suffered adverse events. Suboptimal use of rate control occurred in 47.0% (agent 2.6%; route 27.4%; dosage 9.4%; timing 7.7%). At discharge, 11.5% with CHADS-65 risk factors were still not anticoagulated.

Conclusions: Most patients had a rapid rhythm secondary to a medical cause. There were a concerning number of adverse events related to suboptimal use of rate control. Better awareness of guidelines will ensure safer use of rate control.
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http://dx.doi.org/10.1016/j.cjca.2019.08.040DOI Listing
April 2020

Associations between air pollution and cardio-respiratory physiological measures in older adults exercising outdoors.

Int J Environ Health Res 2019 Dec 12:1-14. Epub 2019 Dec 12.

Department of Geography, Western University, London, Canada.

We examined whether exercising indoors vs. outdoors reduced the cardio-respiratory effects of outdoor air pollution. Adults ≥55 were randomly assigned to exercise indoors when the Air Quality Health Index was ≥5 and outdoors on other days (intervention group, n = 37), or outdoors everyday (control group, n = 35). Both groups completed cardio-respiratory measurements before and after exercise for up to 10 weeks. Data were analyzed using linear mixed effect regression models. In the control group, an interquartile range increase in fine particulate matter (PM) was associated with increases of 1.4% in heart rate (standard error (SE) = 0.7%) and 5.6% (SE = 2.6%) in malondialdehyde, and decreases of 5.6% (SE = 2.5%) to 16.5% (SE = 7.5%) in heart rate variability measures. While the hypothesized benefit of indoor vs. outdoor exercise could not be demonstrated due to an insufficient number of intervention days (n = 2), the study provides evidence of short-term effects of air pollution in older adults. ISRCTN #26552763.
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http://dx.doi.org/10.1080/09603123.2019.1699506DOI Listing
December 2019

A new electrocardiographic definition of left bundle branch block (LBBB) in patients after transcatheter aortic valve replacement (TAVR).

J Electrocardiol 2020 Nov - Dec;63:167-172. Epub 2019 Oct 22.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Canada. Electronic address:

Background: Current LBBB definitions cannot always distinguish LBBB from left ventricular conduction delay. Only patients with LBBB are expected to normalize with His bundle pacing. Patients who develop new LBBB immediately post transcatheter aortic valve replacement (TAVR) provide an excellent model to define electrocardiogram (ECG) features of LBBB. We sought to describe their ECG features and develop a new ECG definition of LBBB.

Methods: We screened ECGs from 264 consecutive patients who underwent TAVR at the University of Ottawa Heart Institute. Patients with a baseline QRS of ≤100 ms who developed QRS ≥120 ms immediately after TAVR were included. Two electrocardiologists reviewed all ECG independently. Baseline demographics and echocardiographic data were retrospectively collected.

Results: 36 patients were included in the analysis. The median age was 85.5 years (IQR, 81.8-89 years) and 52.8% were males. The minimum QRS duration was 126 ms. The median QRS axis was -18° (IQR, -40-4.5°), which is 18.5° leftward compared to the median QRS axis before TAVR. Fourteen patients (38.9%) had left axis deviation. All patients had a notched/slurred R wave in at least one lateral lead and an R wave duration of ≤20 ms in V1 when present.

Conclusion: We developed a new ECG definition of LBBB that includes 2 novel findings: notching/slurring of the R wave in at least one lateral lead and an R wave ≤20 ms in V1. Further larger studies are warranted to confirm these findings.
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http://dx.doi.org/10.1016/j.jelectrocard.2019.10.005DOI Listing
October 2019

A Strategy of Lead Abandonment in a Large Cohort of Patients With Sprint Fidelis Leads.

JACC Clin Electrophysiol 2019 09 28;5(9):1059-1067. Epub 2019 Aug 28.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Canada. Electronic address:

Objectives: This study sought to examine outcomes of our approach to managing a large cohort of patients with Sprint Fidelis (Medtronic, Minneapolis, Minnesota) leads.

Background: The optimal management approach for patients with leads under advisory is unknown. Concerns regarding the risk of device infection and complications associated with delaying lead extraction have recently been suggested to argue against abandoning leads under advisory.

Methods: All patients with a Sprint Fidelis lead implanted at our institute were included. Lead management options were discussed with patients who presented for device surgery at the time of device upgrade, lead fracture, or elective replacement indicator. Implantation of a new lead with abandonment of the Sprint Fidelis lead was the recommended strategy. Patients were subsequently followed at the device clinic at 6-month intervals and were enrolled prospectively in a longitudinal registry.

Results: A total of 520 patients had Sprint Fidelis leads implanted between December 2003 and October 2007 at the study center; 217 patients underwent lead replacement (213 underwent a lead abandonment strategy and 4 underwent a lead extraction strategy). Mean follow-up after lead replacement was 55 ± 33 months. In patients undergoing lead abandonment, 10 of 213 (4.7%) had a procedural complication and 3 of 213 (1.4%) developed subsequent device infection requiring system extraction.

Conclusions: In patients with a Sprint Fidelis lead, implanting a new lead without prophylactic extraction may be a feasible and safe strategy but requires longer follow-up.
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http://dx.doi.org/10.1016/j.jacep.2019.07.006DOI Listing
September 2019

Pregnancy in Catecholaminergic Polymorphic Ventricular Tachycardia.

JACC Clin Electrophysiol 2019 03 26;5(3):387-394. Epub 2018 Dec 26.

Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address:

Objectives: This investigation was a retrospective study of catecholaminergic polymorphic ventricular tachycardia (CPVT) patients in Canada and the Netherlands to compare pregnancy, postpartum, and nonpregnant event rates.

Background: CPVT is characterized by life-threatening arrhythmias during exertion or emotional stress. The arrhythmic risk in CPVT patients during pregnancy is unknown.

Methods: Baseline demographics, genetics, treatment, and pregnancy complications were reviewed. Event rate calculations assumed a 40-week pregnancy and 24-week postpartum period.

Results: Ninety-six CPVT patients had 228 pregnancies (median 2 pregnancies per patient; range: 1 to 10; total: 175.4 pregnant patient-years). The median age of CPVT diagnosis was 40.7 years (range: 12 to 84 years), with a median follow-up of 2.9 years (range: 0 to 20 years; total 448.1 patient-years). Most patients had pregnancies before CPVT diagnosis (82%). Pregnancy and postpartum cardiac events included syncope (5%) and an aborted cardiac arrest (1%), which occurred in patients who were not taking beta-blockers. Other complications included miscarriages (13%) and intrauterine growth restriction (1 case). There were 6 cardiac events (6%) during the nonpregnant period. The pregnancy and postpartum event rates were 1.71 and 2.85 events per 100 patient-years, respectively, and the combined event rate during the pregnancy and postpartum period was 2.14 events per 100 patient-years. These rates were not different from the nonpregnant event rate (1.46 events per 100 patient-years).

Conclusions: The combined pregnancy and postpartum arrhythmic risk in CPVT patients was not elevated compared with the nonpregnant period. Most patients had pregnancies before diagnosis, and all patients with events were not taking beta-blockers at the time of the event.
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http://dx.doi.org/10.1016/j.jacep.2018.10.019DOI Listing
March 2019

Challenge and Impact of Quinidine Access in Sudden Death Syndromes: A National Experience.

JACC Clin Electrophysiol 2019 03 28;5(3):376-382. Epub 2018 Nov 28.

University of British Columbia, Vancouver, British Columbia, Canada. Electronic address:

Objectives: This study sought to determine the nature of quinidine use and accessibility in a national network of inherited arrhythmia clinics.

Background: Quinidine is an antiarrhythmic medication that has been shown to be beneficial in select patients with Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation. Because of the low prevalence of these conditions and restricted access to quinidine through a single regulatory process, quinidine use is rare in Canada.

Methods: Subjects prescribed quinidine were identified through the Hearts in Rhythm Organization that connects the network of inherited arrhythmia clinics across Canada. Cases were retrospectively reviewed for patient characteristics, indications for quinidine use, rate of recurrent ventricular arrhythmia, and issues with quinidine accessibility.

Results: In a population of 36 million, 46 patients are currently prescribed quinidine (0.0000013%, age 48.1 ± 16.1 years, 25 are male). Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation constituted a diagnosis in 13 subjects (28%), 6 (13%), and 21 (46%), respectively. Overall, 37 subjects (81%) had cardiac arrest as an index event. After initial presentation, subjects experienced 7.47 ± 12.3 implantable cardioverter-defibrillator shocks prior to quinidine use over 34.3 ± 45.9 months, versus 0.86 ± 1.69 implantable cardioverter-defibrillator shocks in 43.8 ± 41.8 months while on quinidine (risk ratio: 8.7, p < 0.001). Twenty-two patients access quinidine through routes external to Health Canada's Special Access Program.

Conclusions: Quinidine use is rare in Canada, but it is associated with a reduction in recurrent ventricular arrhythmias in patients with Brugada syndrome, early repolarization syndrome, and idiopathic ventricular fibrillation, with minimal toxicity necessitating discontinuation. Drug interruption is associated with frequent breakthrough events. Access to quinidine is important to deliver this potentially lifesaving therapy.
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http://dx.doi.org/10.1016/j.jacep.2018.10.007DOI Listing
March 2019

The echocardiographic assessment of the right ventricle in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia compared with athletes and matched controls.

Echocardiography 2019 04 18;36(4):666-670. Epub 2019 Mar 18.

Harry Perkins Institute of Medical Research and Fiona Stanley Hospital, The University of Western Australia, Perth, Western Australia, Australia.

Background: There are discrepancies in the quantitative echocardiographic criteria for the right ventricle (RV) between the revised task force criteria (TFC) for Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D) and the guidelines for RV assessment endorsed by American Society of Echocardiography (ASE). Importantly, these criteria do not take into account potential adaptation of the RV to exercise. The goal of this study was to compare the revised TFC quantitative echocardiographic parameters in patients with ARVC/D, athletes and matched controls.

Methods: Echocardiographic parameters of the RV were retrospectively collected in patients who fulfilled the TFC for ARVC/D, an age- matched, sex-matched, and body surface area-matched control population, and athletes (defined as individuals who exercised for more than 7 hours per week). Patients with structural heart disease were excluded in the control and athlete groups.

Results: Twenty patients with ARVC/D, 11 athletes and 20 matched controls were included. There was no significant difference between ARVC/D patients and athletes with the exception of the parasternal long axis right ventricular outflow tract diameter. All parameters were significantly different between ARVC/D patients and the control group. Furthermore, when subjects were categorized into meeting 1 major revised TFC/abnormal ASE criteria or not, only ASE criteria were able to differentiate ARVC/D from control population. Both were unable to differentiate ARVC/D from athletes.

Conclusions: Right ventricle quantitative echocardiographic criteria in the revised TFC are not specific for ARVC/D. Care should be taken in applying these criteria in athletes.
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http://dx.doi.org/10.1111/echo.14308DOI Listing
April 2019

Association Between Patient and Physician Sex and Physician-Estimated Stroke and Bleeding Risks in Atrial Fibrillation.

Can J Cardiol 2019 02 3;35(2):160-168. Epub 2018 Dec 3.

Terrence Donnelly Heart Centre, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada; Canadian Heart Research Centre, Toronto, Ontario, Canada. Electronic address:

Background: Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.

Methods: We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).

Results: Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.

Conclusions: Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation.
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http://dx.doi.org/10.1016/j.cjca.2018.11.023DOI Listing
February 2019

Evaluation of a novel cardioversion intervention for atrial fibrillation: the Ottawa AF cardioversion protocol.

Europace 2019 May;21(5):708-715

Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario, Canada.

Aims: Electrical cardioversion is commonly performed to restore sinus rhythm in patients with atrial fibrillation (AF), but it is unsuccessful in 10-12% of attempts. We sought to evaluate the effectiveness and safety of a novel cardioversion protocol for this arrhythmia.

Methods And Results: Consecutive elective cardioversion attempts for AF between October 2012 and July 2017 at a tertiary cardiovascular centre before (Phase I) and after (Phase II) implementing the Ottawa AF cardioversion protocol (OAFCP) as an institutional initiative in July 2015 were evaluated. The primary outcome was cardioversion success, defined as ≥2 consecutive sinus beats or atrial-paced beats in patients with implanted cardiac devices. Secondary outcomes were first shock success, sustained success (sinus or atrial-paced rhythm on 12-lead electrocardiogram prior to discharge from hospital), and procedural complications. Cardioversion was successful in 459/500 (91.8%) in Phase I compared with 386/389 (99.2%) in Phase II (P < 0.001). This improvement persisted after adjusting for age, body mass index, amiodarone use, and transthoracic impedance using modified Poisson regression [adjusted relative risk 1.08, 95% confidence interval (CI) 1.05-1.11; P < 0.001] and when analysed as an interrupted time series (change in level +9.5%, 95% CI 6.8-12.1%; P < 0.001). The OAFCP was also associated with greater first shock success (88.4% vs. 79.2%; P < 0.001) and sustained success (91.6% vs 84.7%; P=0.002). No serious complications occurred.

Conclusion: Implementing the OAFCP was associated with a 7.4% absolute increase in cardioversion success and increases in first shock and sustained success without serious procedural complications. Its use could safely improve cardioversion success in patients with AF.

Clinical Trial Number: www.clinicaltrials.gov ID: NCT02192957.
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http://dx.doi.org/10.1093/europace/euy285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6479509PMC
May 2019

Early Repolarization Pattern Inheritance in the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry (CASPER).

JACC Clin Electrophysiol 2018 11 29;4(11):1473-1479. Epub 2018 Aug 29.

University of British Columbia, Vancouver, British Columbia, Canada. Electronic address:

Objectives: This study explored early repolarization (ER) pattern inheritance between survivors of unexplained cardiac arrest (UCA) and their first-degree relatives.

Background: ER is considered a factor that confers an increased risk of sudden death. A monogenic explanation for ER is seldom evident after cascade screening.

Methods: UCA survivors and their first-degree relatives enrolled in the CASPER (Cardiac Arrest Survivors With Preserved Ejection Fraction Registry) were included in the study. ER was defined and characterized according to accepted criteria. Logistic regression was performed to explore the association between ER status in the UCA survivor and first-degree relative groups based on the presence of an ER pattern in their related family members after adjusting for age, sex, and ethnicity.

Results: A total of 289 patients from 14 Canadian sites were studied (age: 43.0 ± 15.9 years; 148 women), and 945 electrocardiograms were analyzed. Seventy-five patients had the ER pattern. There was a significantly higher prevalence of the ER pattern in UCA survivors who had first-degree relatives with the ER pattern (adjusted odds ratio: 5.79; 95% confidence intervals [CIs]: 1.79 to 18.7). There was also a nonsignificant higher prevalence of the ER pattern in first-degree relatives of UCA survivors with the ER pattern (OR: 2.43; 95% CI: 0.70 to 8.43). The highest prevalence of the ER pattern was seen in first-degree relatives of UCA survivors with ER syndrome (29%).

Conclusions: The ER pattern appeared to be more common among UCA survivors and first-degree relatives whose related family members had similar changes on electrocardiography, which suggested that genetically complex factors contribute to electrocardiographic patterns that predispose to cardiac arrest.
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http://dx.doi.org/10.1016/j.jacep.2018.07.001DOI Listing
November 2018

Characterization of Low-Voltage Areas in Patients With Atrial Fibrillation: Insights From High-Density Intracardiac Mapping.

Can J Cardiol 2018 08 12;34(8):1033-1040. Epub 2018 Apr 12.

Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.

Background: There is limited data on the scar burden in patients with atrial fibrillation (AF). In this study, we sought to evaluate the presence and extent of an abnormal left atrial (LA) substrate in patients with paroxysmal or persistent AF.

Methods: Consecutive patients who underwent initial AF catheter ablation were prospectively enrolled. Endocardial voltage mapping was acquired in sinus rhythm using multipolar mapping catheters. Automated software was used to ensure homogeneous data collection. Assessment of low-voltage area (LVA) was performed by a reviewer blinded to clinical details.

Results: One hundred and four patients were prospectively enrolled; 69 had paroxysmal and 35 persistent AF. The mean LA volume was 159 ± 48 mL, and the average number of LA points collected was 1308 ± 1065. Atrial LVAs were present in 23 of 69 (33%) subjects with paroxysmal and 20 of 35 (57%) with persistent AF (P = 0.02). Amongst 43 of 104 patients with scar, the average extent of LVA was 19.4 ± 21.6 cm and the mean percentage area was 7.6 ± 8.8%. Univariate analysis showed that age, LA volume, and persistent AF were associated with the presence of LVA. Multivariable analysis showed that age (odds ratio [OR] 1.05; 95% confidence interval [CI] 1.00-1.11; P = 0.046) and LA volume (OR 1.02; 95% CI 1.01-1.04; P < 0.001) remained predictors of LVA. AF classification (persistent vs paroxysmal) was not a predictor of an abnormal atrial substrate (OR 1.34; 95% CI 0.4-3.9; P = 0.56).

Conclusions: There is wide variability in the presence and extent of LVA in patients with paroxysmal or persistent AF. Age and LA volume were predictors of LVA. There was no correlation between AF classification and the presence of LVA.
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http://dx.doi.org/10.1016/j.cjca.2018.04.008DOI Listing
August 2018

Prevalence of left atrial appendage thrombus detected by transoesophageal echocardiography before catheter ablation of atrial fibrillation in patients anticoagulated with non-vitamin K antagonist oral anticoagulants.

Europace 2019 Jan;21(1):48-53

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, 40 Ruskin St, Ottawa, ON, Canada.

Aims: There is ongoing controversy about the need for routine transoesophageal echocardiography (TOE) prior to atrial fibrillation (AF) ablation. Recently, the debate was reignited by the publication of a large series of patients showing a prevalence of left atrial appendage thrombus (LAAT) on TOE of 4.4%. We sought to assess the prevalence of LAAT on TOE before AF ablation at our institution.

Methods And Results: Consecutive patients scheduled for AF ablation at our institution between January 2009 and December 2016 were included. All patients were on oral anticoagulation for at least 4 weeks prior to TOE. Transoesophageal echocardiographies were performed 3-5 days prior to scheduled AF ablation. Data were collected utilizing a prospective database. In all, 668 patients and 943 AF ablation procedures were included. Mean age was 64 ± 11 years, 72% were male, average CHADS2 score was 1.0 ± 1.0, and 72% of the patients had paroxysmal AF. At the time of ablation, 496 (53%) were on non-vitamin K antagonist oral anticoagulants (NOACs) and 447 (47%) were on Warfarin. There were three cases with LAAT (3/943, 0.3%), all of whom had persistent AF and were on Warfarin. Two patients underwent surgical ablation and the third patient did not undergo ablation.

Conclusion: In our experience, the prevalence of LAAT in patients on anticoagulation therapy undergoing TOE before catheter ablation of AF is 0.3%, which was much lower than recently reported. None of the patients with paroxysmal AF or on NOACs were found to have LAAT. Rather than routine use of TOE prior to AF ablation, a risk-based approach should be considered.
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http://dx.doi.org/10.1093/europace/euy129DOI Listing
January 2019

Swallowing-induced atrial tachycardia.

CMAJ 2018 04;190(16):E507-E509

Adult Cardiology Residency Program (Mathew); Arrhythmia Service (Green, Nery), Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ont.

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http://dx.doi.org/10.1503/cmaj.171261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915248PMC
April 2018

Cardiorespiratory Effects of Air Pollution in a Panel Study of Winter Outdoor Physical Activity in Older Adults.

J Occup Environ Med 2018 08;60(8):673-682

Population Studies Division, Health Canada, Vancouver, British Columbia and Ottawa, Ontario (Dr Stieb, Dr Shutt, Dr Kauri, Dr Szyszkowicz, Dr Chen, Jovic, Dr Liu, Dr Dales), School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario (Dr Stieb), British Columbia Ministry of Environment and Climate Change Strategy, Prince George, British Columbia (Ms Roth), Air Health Science Division, Health Canada, Vancouver, British Columbia and Ottawa, Ontario (Ms Dobbin, Mr Van Ryswyk, Mr Kulka, Dr Weichenthal), Hazard Identification Division, Health Canada, Ottawa, Ontario (Mr Rigden, Dr Pelletier), University of Ottawa Heart Institute, Ottawa, Ontario (Ms Mulholland, Dr Green), Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Quebec (Dr Weichenthal), and Department of Medicine, University of Ottawa, Ottawa, Ontario (Dr Dales), Canada.

Objective: The aim of this study was to assess cardiorespiratory effects of air pollution in older adults exercising outdoors in winter.

Methods: Adults 55 years of age and older completed daily measurements of blood pressure, peak expiratory flow and oximetry, and weekly measurements of heart rate variability, endothelial function, spirometry, fraction of exhaled nitric oxide and urinary oxidative stress markers, before and after outdoor exercise, for 10 weeks. Data were analyzed using linear mixed effect models.

Results: Pooled estimates combining 2014 (n = 36 participants) and 2015 (n = 34) indicated that an interquartile increase in the Air Quality Health Index was associated with a significant (P < 0.05) increase in heart rate (0.33%) and significant decreases in forced expiratory volume (0.30%), and systolic (0.28%) and diastolic blood pressure (0.39%).

Conclusion: Acute subclinical effects of air pollution were observed in older adults exercising outdoors in winter.
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http://dx.doi.org/10.1097/JOM.0000000000001334DOI Listing
August 2018

Bidirectional ventricular tachycardia in ischemic cardiomyopathy during ablation.

HeartRhythm Case Rep 2017 Nov 5;3(11):527-530. Epub 2017 Sep 5.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.

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http://dx.doi.org/10.1016/j.hrcr.2017.08.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5778102PMC
November 2017

Multiple inappropriate implantable cardiac defibrillator therapies in rapid succession.

Clin Case Rep 2017 12 23;5(12):1972-1975. Epub 2017 Oct 23.

Division of Cardiology University of Ottawa Heart Institute Ottawa ON Canada.

Inappropriate implantable cardiac defibrillator (ICD) shocks are associated with significant morbidity and have the potential to trigger ventricular arrhythmias, cardiac decompensation, and death. We present a case of multiple inappropriate ICD therapies in rapid succession due electromagnetic interference from a Dr-Ho's transcutaneous electric nerve stimulator machine, and subsequently from a faulty electrical outlet.
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http://dx.doi.org/10.1002/ccr3.1222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5715425PMC
December 2017

Loss-of-Function Variants: True Monogenic Culprits of Long-QT Syndrome or Proarrhythmic Variants Requiring Secondary Provocation?

Circ Arrhythm Electrophysiol 2017 Aug;10(8)

For author affiliations, please see the Appendix.

Background: Insight into type 6 long-QT syndrome (LQT6), stemming from mutations in the -encoded voltage-gated channel β-subunit, is limited. We sought to further characterize its clinical phenotype.

Methods And Results: Individuals with reported pathogenic mutations identified during arrhythmia evaluation were collected from inherited arrhythmia clinics and the Rochester long-QT syndrome (LQTS) registry. Previously reported LQT6 cases were identified through a search of the MEDLINE database. Clinical features were assessed, while reported mutations were evaluated for genotype-phenotype segregation and classified according to the contemporary American College of Medical Genetics guidelines. Twenty-seven probands possessed reported pathogenic mutations, while a MEDLINE search identified 17 additional LQT6 cases providing clinical and genetic data. Sixteen probands had normal resting QTc values and only developed QT prolongation and malignant arrhythmias after exposure to QT-prolonging stressors, 10 had other LQTS pathogenic mutations, and 10 did not have an LQTS phenotype. Although the remaining 8 subjects had an LQTS phenotype, evidence suggested that the variant was not the underlying culprit. The collective frequency of variants implicated in LQT6 in the Exome Aggregation Consortium database was 1.4%, in comparison with a 0.0005% estimated clinical prevalence for LQT6.

Conclusions: On the basis of clinical phenotype, the high allelic frequencies of LQT6 mutations in the Exome Aggregation Consortium database, and absence of previous documentation of genotype-phenotype segregation, our findings suggest that many variants, and perhaps all, have been erroneously designated as LQTS-causative mutations. Instead, variants may confer proarrhythmic susceptibility when provoked by additional environmental/acquired or genetic factors, or both.
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http://dx.doi.org/10.1161/CIRCEP.117.005282DOI Listing
August 2017

Crossing the slow pathway bridge: A better method for decreasing long-term recurrences after cryoablation of atrioventricular nodal reentrant tachycardia?

Heart Rhythm 2017 11 29;14(11):1655-1656. Epub 2017 Jul 29.

University of Ottawa Heart Institute, Ottawa, Ontario, Canada. Electronic address:

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http://dx.doi.org/10.1016/j.hrthm.2017.07.031DOI Listing
November 2017

Use of Evidence-Based Therapy for Cardiovascular Risk Factors in Canadian Outpatients With Atrial Fibrillation: From the Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation (FREEDOM AF) and Co-ordinated National Network to Engage Physicians in the Care and Treatment of Patients With Atrial Fibrillation (CONNECT AF).

Am J Cardiol 2017 Aug 1;120(4):582-587. Epub 2017 Jun 1.

Canadian Heart Research Centre, Toronto, Ontario, Canada; Division of Cardiology, Terrence Donnelly Heart Centre, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Electronic address:

Using data collected from 2 national atrial fibrillation (AF) primary care physician chart audits (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation [FREEDOM AF] and Co-ordinated National Network to Engage Physicians in the Care and Treatment of Patients With Atrial Fibrillation [CONNECT AF]), we evaluated the frequency of, and factors associated with, the use of cardiovascular (CV) evidence-based therapies in Canadian AF outpatients with at least 1 CV risk factor or co-morbidity. Of the 11,264 patients enrolled, 9,495 (84.3%) were eligible for one or more CV evidence-based therapies. The proportions of patients with AF receiving all eligible guideline-recommended therapies were 40.8% of patients with coronary artery disease, 48.9% of patients with diabetes mellitus, 40.2% of patients with heart failure, 96.7% of patients with hypertension, and 55.1% of patients with peripheral arterial disease. Factors that were independently associated with nonreceipt of all indicated evidence-based therapies included sinus rhythm rather than AF at baseline and liver disease. In conclusion, although most Canadian outpatients with AF have CV risk factors or co-morbidities, a substantial portion of these patients did not receive all guideline-recommended therapies. These findings suggest that there is an opportunity to improve the quality of care for patients with AF in Canada.
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http://dx.doi.org/10.1016/j.amjcard.2017.05.027DOI Listing
August 2017

Three-year outcomes and reconnection patterns after initial contact force guided pulmonary vein isolation for paroxysmal atrial fibrillation.

J Cardiovasc Electrophysiol 2017 Sep 1;28(9):984-993. Epub 2017 Sep 1.

Arrhythmia Service, Division of Cardiology, University of Ottawa Heart Institute, Canada.

Background And Objective: Contact force (CF) sensing is a novel technology used for catheter ablation of atrial fibrillation (AF). We compared the single procedure success of CF-guided pulmonary vein isolation (PVI) with that of non-CF guided PVI during a 3-year (1,095 days) follow up period and analyzed the pattern of pulmonary vein (PV) reconnection.

Methods: A cohort of 167 subjects (68 CF vs. 99 non-CF) with paroxysmal AF were included in the study. Atrial arrhythmia (AA) recurrence was defined as documented AF, atrial flutter, or atrial tachycardia lasting >30 seconds and occurring after 90 days.

Results: Subjects in the CF group showed a statistically nonsignificant improvement in AA free survival compared to those in the non-CF group (66.2% vs. 51.5%; P value: 0.06). A greater propensity for reconnection was noted around the right-sided PVs compared to left-sided PVs related in both catheter ablation groups. For example, in the CF group 36% of right-sided segments reconnected compared to 16% of left-sided segments (P value <0.01).

Conclusions: A greater propensity for reconnection was noted around the right sided PV segments in both the CF and non-CF groups. The explanation for this finding was related to greater catheter instability around the right sided veins. Further research is needed to explore the utility of a "real-time" composite indicator that includes RF energy, CF and catheter stability in predicting transmural lesion formation during catheter ablation.
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http://dx.doi.org/10.1111/jce.13280DOI Listing
September 2017