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Contact-force (CF) catheters appear to be more effective compared to standard ablation catheters for complex radiofrequency ablation including atrial fibrillation (AF) ablation when optimal CF10 g is achieved. Some have suggested that this technology could also improve procedural safety. We report 2 cases of atrioesophageal fistulae (AEF), a rare but catastrophic complication of AF ablation. These are to our knowledge the first cases of AEF described after using CF catheters.

We would like to thank Professors Jaimez and Sanchez for their letter of response commenting on our recent summary of evaluation and outcome of our first 200 unexplained cardiac arrest probands.1 We would first like to point out that we excluded patients with a manifest diagnosis, so none of these patients had overt evidence of an ion channelopathy or cardiomyopathy that are typically both readily diagnosed and treated. This is reflected in our empirical strength of diagnosis framework, which is necessary when a classic diagnosis is not forthcoming.2 In addition, registries do not mandate care but rather capture it, and reflect the reality of practice with the vagaries of contextual clinical decision making. In response to the concerns about the incidence of shocks and the inefficacy of medical therapy, it is important to point out the difference between efficacy and effectiveness. Without …

Background— The Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) enrolls patients with apparently unexplained cardiac arrest and no evident cardiac disease to identify the pathogenesis of cardiac arrest through systematic clinical testing. Exercise testing, drug provocation, advanced cardiac imaging, and genetic testing may be useful when a cause is not apparent. Methods and Results— The first 200 survivors of unexplained cardiac arrest from 14 centers across Canada were evaluated to determine the results of investigation and follow-up (age, 48.6±14.7 years, 41% female). Patients were free of evidence of coronary artery disease, left ventricular dysfunction, or evident repolarization syndromes. Advanced testing determined a diagnosis in 34% of patients at baseline, with a diagnosis emerging during follow-up in 7% of patients. Of those who were diagnosed, 28 (35%) had an underlying structural condition and 53 (65%) had a primary electric disease. During a mean follow-up of 3.15±2.34 years, 23% of patients had either a shock or an appropriate antitachycardia pacing from their implantable cardioverter defibrillator, or both. The implantable cardioverter defibrillator appropriate intervention rate was 8.4% at 1 year and 18.1% at 3 years, with no clear difference between diagnosed and undiagnosed subjects, or between those diagnosed with a primary electric versus structural pathogenesis. Conclusions— Obtaining a diagnosis in previously unexplained cardiac arrest patients requires systematic clinical testing and regular follow-up to unmask the cause. Nearly half of apparently unexplained cardiac arrest patients ultimately received a diagnosis, allowing for improved treatment and family screening. A substantial proportion of patients received appropriate implantable cardioverter defibrillator therapy during medium-term follow-up. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00292032.

Poor R-wave progression (PRWP) in the precordial leads on random ECG is relatively frequent in the general population and includes a broad differential diagnosis. Here, we present for the first time a case of complete absence of precordial R waves associated with a prominent R wave in aVR due to the absence of the left-sided pericardium in a 44-year-old woman who experienced sudden cardiac death.

Congenital absence of the pericardium is a very rare cardiac malformation, usually diagnosed fortuitously on autopsy or surgery. Symptoms related to these abnormalities are usually benign, and fatalities reported in the literature are almost exclusively secondary to herniation of the heart through a partial defect. We present the unusual case of a 44-year-old woman admitted for sudden cardiac arrest. Initial evaluation suggested acute anterior myocardial infarction, but further investigation ruled out coronary heart disease. No arrhythmia could be initiated on electrophysiological study, and absence of most of the left pericardium was confirmed by cardiac magnetic resonance imaging. After the exclusion of common etiologies such as idiopathic ventricular fibrillation, transient great vessel torsion due to hypermobility of the heart with secondary malignant arrhythmia was considered to be the most likely mechanism for the sudden cardiac arrest. A review of the available literature on clinical presentation, diagnostic tools, and therapeutic options is also presented.

Background Following recent cases of nonphysiologic noise noted early after defibrillator implantation, the Canadian Heart Rhythm Society Device Committee decided to evaluate the implications of this problem. Objective To determine the incidence and consequences of nonphysiologic noise early after defibrillator implantation. Methods The Canadian Heart Rhythm Society Device Committee surveyed all Canadian defibrillator implanting centers regarding their implant volumes and number of cases where nonphysiologic noise had been noted early ( Results Responses were obtained from 20 of 23 surveyed implanting centers, with a total implant volume of 4960 defibrillators per year. The occurrence of nonphysiologic noise early after implantation was noted in 25 cases over the preceding 2 years (0.25%). Noise was detected in devices of all 3 of the leading volume device manufacturers. There were 2 cases of inappropriate shocks and 2 cases of symptomatic pacing inhibition. In 4 cases, removal of the lead from the header and retesting with the analyzer confirmed normal lead function. In all cases, the noise resolved within 24 hours. Conclusion Nonphysiologic noise early after defibrillator implantation was noted in 0.25% of procedures and was not limited to one specific manufacturer. This noise may result in an inappropriate shock or inhibition of pacing in a pacemaker-dependent patient. This transient phenomenon, possibly related to fluid and/or air in the header, appears to always resolve without surgical intervention.

Propafenone and its 5-hydroxy metabolite exhibit different electrophysiological properties. Objectives of the CAQ-PAF study were (1) to develop a strategy favoring propafenone instead of 5-hydroxypropafenone in plasma following oral administration of propafenone and (2) to evaluate the potential of low-dose quinidine to chronically inhibit CYP2D6. Patients (n = 102) with atrial fibrillation received propafenone 150 mg 3 times daily with either quinidine 100 mg twice daily or placebo. Throughout the study (follow-up, 199 ± 155 days), quinidine successfully inhibited CYP2D6: propafenone concentrations were 3 times higher in patients receiving quinidine (1033 ± 611 ng/mL vs 328 ± 229 ng/mL; P < .001). Moreover, 80% (n = 10) of patients with propafenone levels greater than 1500 ng/mL were in sinus rhythm at 1 year. In contrast, recurrence of atrial fibrillation occurred in 22 of 23 patients with propafenone levels less than 1000 ng/mL (P < .0001). Thus, chronic inhibition of CYP2D6 is achievable with low-dose quinidine in humans. Increased plasma levels of propafenone may be highly beneficial to prevent recurrence of atrial fibrillation.

Sentinel Symptoms in Unexplained Cardiac Arrest. Background: Warning symptoms may provide an opportunity to diagnose genetic disorders leading to preventative therapy. We explored the symptom history of patients with apparently unexplained cardiac arrest to determine the frequency of sentinel symptoms. Methods: Patients with apparently unexplained cardiac arrest and no evident cardiac disease underwent systematic clinical evaluation. Patients and first-degree relatives were interviewed to determine the presence of cardiac symptoms, and those with syncope underwent 2 structured Calgary Syncope Score questionnaires to determine the probable mechanism of syncope. Results: One hundred consecutive cardiac arrest patients (age 43.0 ± 13.4 years, 60% male) and 63 first-degree relatives (age 37.6 ± 16.3 years, 54% female) were enrolled. Previous cardiac symptoms were present in 69% of cardiac arrest patients compared to 43% of family members (P = 0.001). Prior syncope was present in 26% of cardiac arrest patients, compared to 22% of family members (P = 0.59). Twenty-four of 25 cardiac arrest patients who completed the syncope questionnaires had a syncope versus seizure score

Objectives We evaluated the prevalence and characteristics of early repolarization in patients in CASPER (Cardiac Arrest Survivors With Preserved Ejection Fraction Registry). Background Early repolarization has been implicated in a syndrome of polymorphic ventricular tachycardia and fibrillation in patients without organic heart disease. Methods One hundred patients with apparently unexplained cardiac arrest and preserved ejection fraction underwent extensive clinical and genetic testing to unmask subclinical electrical or structural disease. A blinded independent analysis of the 12-lead electrocardiogram (ECG) was performed. Early repolarization was defined as ≥0.1 mV QRS-ST junction (J-point) elevation with terminal QRS slurring or notching in at least 2 contiguous inferior and/or lateral leads. Results One hundred cardiac arrest patients were enrolled (40 females, age 43 ± 14 years). Forty-four were diagnosed with an established cause for cardiac arrest. Significant early repolarization was found in 19 patients, including 6 with a primary diagnosis that explained their cardiac arrest (14%), compared with 23% of the 56 patients with idiopathic ventricular fibrillation (IVF) (p = 0.23). J-point elevation in IVF patients had higher amplitude (0.25 ± 0.11 mV vs. 0.13 ± 0.05 mV, p = 0.02) and wider distribution (4.3 ± 1.3 leads vs. 2.8 ± 0.8 leads; p = 0.01) than those with an established cause of cardiac arrest. J-wave amplitude was fluctuant on serial ECGs; at least 1 ECG failed to demonstrate early repolarization in 58% of patients. Conclusions Early repolarization is present in a significant proportion of causally diagnosed and idiopathic VF. It is often intermittent and more pronounced in IVF patients. (Registry of Unexplained Cardiac Arrest; NCT00292032).

Patients undergoing left atrial ablation require transseptal puncture, which can be challenging, even for experienced physicians. This study compared the efficacy and safety of radiofrequency (RF) energy transseptal punctures to conventional approach.Patients requiring transseptal puncture for left atrial access were included using either conventional approach or the NRG™ RF transseptal needle as first attempt. Procedure time for transseptal access, fluoroscopy time, crossover, and safety of both techniques were compared.A total of 241 transseptal punctures were performed in 148 consecutive patients (114 men, 54 ± 10 years, left atrial volume 32 ± 10 ml/m(2)) who underwent 157 procedures with left atrial access, mainly for atrial fibrillation. It was a repeat transseptal procedure in 49 patients. Procedures were guided by transesophageal echocardiography. RF transseptal puncture was planned in 119 procedures. RF was delivered in 98 procedures (82%) for 139/187 punctures: 48 punctures did not require RF, including 25 punctures performed by exposing the needle tip, 22 through patent foramen ovale, and 1 RF delivery failure by the generator. Average time for RF transseptal was 4.8 ± 2.8 min compared to 7.5 ± 8.5 min for conventional approach (p = 0.045). Fluoroscopy time was 1.8 ± 1.3 min for RF transseptal and 2.9 ± 2.8 min for standard approach (p = 0.043). Four patients required crossover to RF transseptal needle in the conventional group (p = 0.003). One tamponade occurred at the end of procedure in a patient using the RF needle, and one interatrial septum dissection with aortic root hematoma occurred in the conventional group.Transseptal needle puncture using RF energy can be performed safely and quickly under imaging guidance.

The era of gene discovery and molecular medicine has had a significant impact on clinical practice. Knowledge of specific genetic findings causative for or associated with human disease may enhance diagnostic accuracy and influence treatment decisions. In cardiovascular disease, gene discovery for inherited arrhythmia syndromes has advanced most rapidly. The arrhythmia specialist is often confronted with the challenge of diagnosing and managing genetic arrhythmia syndromes. There is now a clear need for guidelines on the appropriate use of genetic testing for the most common genetic conditions associated with a risk of sudden cardiac death. This document represents the first ever published recommendations outlining the role of genetic testing in various clinical scenarios, the specific genes to be considered for testing, and the utility of test results in the management of patients and their families.

SELECT AF Methodology & Rationale. Background: Adjuvant ablation of complex fractionated atrial electrograms (CFAE) in addition to pulmonary vein isolation (PVI) likely improves procedural outcome compared to PVI alone, particularly in patients with persistent atrial fibrillation (AF). However, CFAE regions can be extensive, occasionally requiring a large amount of extra ablation. Some CFAE regions may also represent passive wavefront collision and may not require ablation. Thus, there is interest in identifying more selective CFAE sites that are critical to AF perpetuation, minimizing the amount of adjuvant ablation that must be performed. Objective: The SELECT AF study is a prospective, multicenter, randomized trial comparing a strategy of PVI plus generalized CFAE ablation versus a strategy of PVI plus selective CFAE ablation, focusing on regions of continuous electrical activity (CEA). The primary efficacy endpoint is freedom from atrial arrhythmia at 1 year and the primary safety endpoint is total radiofrequency (RF) delivery time per procedure. Methods: Patients undergoing a first time ablation procedure for symptomatic persistent AF will be included. Patients with permanent AF or with left atrial size ≥55 mm will be excluded. Patients will all receive PVI at the time of their ablation, but will be randomized 1:1 to receive adjuvant CFAE ablation using the traditional “generalized” approach, or a “selective” approach targeting only CEA regions. Both strategies will be guided by automated mapping algorithms. This study will enroll a minimum of 80 evaluable subjects; 40 in each randomization group. Conclusions: SELECT AF is a randomized trial in patients with persistent AF to evaluate the efficacy of selective versus generalized CFAE ablation in addition to traditional PVI. (J Cardiovasc Electrophysiol, Vol. 22, pp. 541-547 May 2011)

Background Benefits of cardiac resynchronisation therapy (CRT) in patients with heart failure (HF) and left bundle branch block (LBBB) have been well established. The presence of asynchronism and viability predicts response to CRT with good accuracy. Viability in the region of the pacing lead as predictor of response to CRT in patients with HF, intraventricular asynchrony and right bundle branch block (RBBB) has never been evaluated. Methods We studied 4 consecutive patients with RBBB (QRS>120 ms) advanced ischemic HF, low ejection fraction (≤35%) and intraventricular asynchrony ≥50 ms scheduled for CRT. Dobutamine stress echocardiography (DSE) was performed within the week before CRT. Viability was defined as increased wall thickening during DSE. Viability in the region of left ventricular (LV) pacing lead was defined as the presence of viability in 2 contiguous segments. Response was defined by LV reverse remodeling (i.e. ≥15% reduction in LV end-systolic volume) 3–6 months after CRT. Results Three patients demonstrated LV reverse remodeling at follow-up. Responders showed LV end-systolic volume decrease of −31±16% from baseline to follow-up whereas no change was observed in the non responder patient. Similar LV asynchronism was found in all patients. All responders had viability in ≥2 segments in the region of LV pacing. Conclusion This preliminary report suggests that similar reverse remodeling can be observed in RBBB patients as patients with LBBB after CRT. Intraventricular asynchrony and RBBB, viability in the region of pacing lead may help to predict response to CRT in patients with HF.

This study investigated the impact of ischemic mitral regurgitation (MR) severity and viability on left ventricular (LV) reverse remodeling after cardiac resynchronization therapy (CRT) in patients with ischemic cardiomyopathy. Severe MR and ischemic cardiomyopathy have been associated with lack of LV reverse remodeling after CRT. Fifty-seven consecutive patients with ischemic MR, LV ejection fractionor =35%, QRS durationor =120 ms, and intraventricular dyssynchronyor =50 ms were prospectively included. Stress echocardiography was performed before CRT implantation. Viability in the region of the LV pacing lead was defined as the presence of viability in 2 contiguous segments. Response to CRT at 6 months was defined by evidence ofor =15% LV decrease in end-systolic volume. Severe MR was defined by an effective regurgitant orifice (ERO) areaor =20 mm(2). Thirty-three patients (58%) were responders at follow-up. Baseline ERO area and prevalence of severe MR were not different between responders and nonresponders (19 +/- 11 vs 21 +/- 13 mm(2), p = 0.67; 52% vs 53%, p = 0.84). In responders, MR was decreased by 58% (ERO 19 +/- 12 to 8 +/- 6 mm(2)). In the presence of viability in the region of the pacing lead, 74% (n = 29 patients) were responders (sensitivity 88%, specificity 58%); in the subgroup of patients with viability in the region of the pacing lead and severe MR, 83% (n = 17 patients) were responders. In conclusion, LV remodeling is frequent and ischemic MR decrease important in patients with viability in the region of the pacing lead without regard to MR severity.

Background: The presence of viable myocardium may predict response to cardiac resynchronization therapy (CRT). The aim of this study is to evaluate in patients with left ventricular (LV) dyssynchrony whether response to CRT is related to myocardial viability in the region of the pacing lead. Methods: Forty-nine consecutive patients with advanced heart failure, LV ejection fraction 120 ms and intraventricular asynchronism ≥ 50 ms were included. Dobutamine stress echocardiography was performed within the week before CRT implantation. Resting echocardiography was performed 6 months after CRT implantation. Viability in the region of LV pacing lead was defined as the presence of viability in two contiguous segments. Response to CRT was defined by evidence of reverse LV remodeling (≥15% reduction in LV end-systolic volume). Results: Thirty-one patients (63%) were identified as responders at follow-up. The average of viable segments was 5.9 ± 2 in responders and 3.2 ± 3 in nonresponders (P = 0.0003). Viability in the region of the pacing lead had a sensitivity of 94%, a specificity of 67%, a positive predictive value of 83%, and a negative predictive value of 86% for the prediction of response to CRT. Conclusions: In patients with LV dyssynchrony, reverse remodeling after CRT requires viability in the region of the pacing lead. This simple method using echocardiography dobutamine for the evaluation of local viability (i.e., viability in two contiguous segments) may be useful to the clinician in choosing the best LV lead positioning. (Echocardiography 2010;27:668-676)

Background— The study was conducted to compare relative safety and efficacy of pulmonary vein antrum isolation (PVAI) using intracardiac echocardiographic guidance and circumferential pulmonary vein ablation (CPVA) for atrial fibrillation (AF) using radiofrequency energy. Methods and Results— Sixty patients (81% men; 81% paroxysmal; age, 56�8 years) failing 2�1 antiarrhythmic drugs were randomly assigned to undergo CPVA (n=30) or PVAI (n=30) at 5 centers between December 2004 and October 2007. CPVA patients had circular lesions placed at least 1 cm outside of the veins. Ipsilateral veins were ablated en block with the end point of disappearance of potentials within the circular lesion. Left atrial roof line and mitral isthmus line were ablated without verification of block. For patients in AF postablation or with AF induced with programmed stimulation, complex fractionated electrograms were mapped and ablated to the end point of AF termination or disappearance of complex fractionated electrograms. PVAI did not include complex fractionated electrogram ablation. Esophageal temperature was monitored and kept within 2�C of baseline or under 39�C. Success was defined as absence of atrial tachyarrhythmias (AF/AT) off antiarrhythmic drugs. There was no difference between CPVA and PVAI regarding to baseline variables, catheter used, duration of the procedure, or RF delivery. Fluoroscopy time was longer with PVAI (54�17 minutes versus 77�18 minutes, P =0.0001). No significant complications occurred in either arm. PVAI was more likely to achieve control of AF/AT off antiarrhythmic drugs (57% versus 27%, P =0.02) at 2�1 years of follow-up. Conclusions— A single PVAI procedure is more likely to result in freedom from AF/AT off antiarrhythmic drugs than CPVA supplemented by complex fractionated electrogram ablation in select patients.

Background Catheter ablation is a curative treatment with excellent success and minimal complication rates for patients with supraventricular or ventricular arrhythmias. Methods The acute outcomes and complications of all catheter ablation procedures for supraventricular and ventricular arrhythmias performed at the Quebec Heart Institute (Sainte-Foy, Quebec) during a 14-year period from January 1, 1993, to December 31, 2006, were prospectively assessed. The ablation procedures were classified according to the arrhythmias induced using standard electrophysiological techniques and definitions. Immediate success and complication rates were prospectively included in the database. Results A total of 5330 patients had catheter ablation performed at the Institute during the period assessed. The mean (± SD) age of patients was 50±18 years (range four to 97 years), and 2340 patients (44%) were men. Most of the patients were younger than 75 years (group 1), and 487 (9%) were 75 years of age and older (group 2). Indications for ablations were as follows: atrioventricular nodal reentry tachycardia (AVNRT) in 2263 patients, accessory pathways in 1147 patients, atrioventricular node ablation in 803 patients, typical atrial flutter in 377 patients and atrial tachycardia in 160 patients; 580 patients had other ablation procedures. The overall success rates were 81% for atrial tachycardia, 92% for accessory pathways or flutter, and 99% for AVNRT or atrioventricular node ablation. There was no difference in the success rates of the younger (group 1) and older (group 2) patients. Seventy-seven patients (1.4%) had complications, including 11 major events (myocardial infarction in one patient, pulmonary embolism in three patients and permanent pacemaker in seven patients). In patients undergoing AVNRT ablation, two had a permanent pacemaker implanted immediately after the procedure and three had a permanent pacemaker implanted at follow-up. Conclusions The results confirm that radiofrequency ablation is safe and effective, supporting ablation therapy as a first-line therapy for the majority of patients with cardiac arrhythmias.

Introduction: Patients with Brugada syndrome (BrS) are at risk for ventricular arrhythmias (VAs) and sudden death. Identification of high-risk individuals beyond those with syncope or resuscitated SCD remains a major challenge. We sought to assess the value of clinical, electrophysiological, and ECG features of depolarization and repolarization in predicting arrhythmic events and SCD in a Quebec population. Methods: Consecutive patients with BrS diagnosed between 2002 and 2013 were recruited from three major university hospitals in the province of Quebec, Canada. Relevant clinical features were recorded at baseline. Qualifying ECGs with the highest type 1 ST-segment elevations were reviewed and analyzed by two electrophysiologists blinded to clinical history, with the following parameters assessed: S duration in V1, aVR sign, QRS duration in V6, R-J interval in V2, maximal Tp-e, duration, Tp-e dispersion, QRS-f, ST elevation and QTc in V2, and presence of an inferolateral ER pattern. Survival analyses considered a left truncation model to account for potential sampling bias, considering that those who died suddenly before recognition of BrS were necessarily excluded. Results: A total of 105 consecutive patients, 79.8% male, were diagnosed with BrS at a median age of 48 years and were followed for 5.0±1.2 years. Ten (9.5%) had a history of SCD, 37 (35.2%) had syncope, and 7 (6.7%) experienced 20 arrhythmic events during follow-up (7 anti-tachycardia pacing; 13 shocks). In multivariate Cox regression analyses adjusted for left truncation and Firth bias correction, a spontaneous type I ECG pattern (HR 10.80; 95% CI 1.03 to 113.87; p=0.0476)], maximal Tp-e duration ≥100ms (HR 29.73; 95% CI 1.33 to 666.37; p= 0.0325) and QRS duration in V6>110 ms (HR 15.27; 95% CI 1.07 to 217.42; p=0.0443) were independently associated with VAs or aborted SCD. Family history of SCD, AF, and inducible VAs during programmed ventricular stimulation were not associated with the primary endpoint. Conclusion: In a cohort of patients with BrS from the province of Quebec, VAs and SCD were independently associated with standard 12-lead ECG features including a spontaneous type 1 pattern, depolarization (QRS in V6 >110 ms), and repolarization (maximal Tp-e duration) criteria.

Background— Many patients with implanted cardioverter defibrillators (ICDs) receive adjunctive antiarrhythmic drug therapy, most commonly amiodarone or sotalol. The effects of these drugs on defibrillation energy requirements have not been previously assessed in a randomized controlled trial. Methods and Results— The Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) trial was a randomized clinical trial evaluating the efficacy of amiodarone plus β-blocker and sotalol versus β-blocker alone for reduction of ICD shocks. Within OPTIC, a prospectively designed substudy evaluated the effects of the 3 treatment arms on defibrillation energy requirements. Defibrillation thresholds (DFTs) were measured (binary step-down protocol) at baseline and again after 8 to 12 weeks of therapy in 94 patients, of whom 29 were randomized to receive β-blocker therapy (control group), 35 to amiodarone plus β-blocker, and 30 to sotalol. In the control group, the mean DFT decreased from 8.77±5.15 J at baseline to 7.13±3.43 J ( P =0.027); in the amiodarone group, DFT increased from 8.53±4.29 to 9.82±5.84 J ( P =0.091). In the sotalol group, DFT decreased from 8.09±4.81 to 7.20±5.30 J ( P =0.21). DFT changes in the β-blocker and the amiodarone group were significantly different ( P =0.006). In all patients, adequate safety margins for defibrillation were maintained. No clinical variable predicted baseline DFT or changes in DFT on therapy. Conclusion— Although amiodarone increased DFT, the effect size with modern ICD systems is very small. Therefore, DFT reassessment after the institution of antiarrhythmic drug therapy with amiodarone or sotalol is not routinely required.

Background Brugada syndrome (BS) and long QT syndrome (LQTS) are electrical disorders with a genetic background. They are revealed on surface electrocardiograms as either right bundle branch block and ST segment elevation in the right pericardial leads (V1, V2 and V3) in BS or as a long QTc interval on all 12 leads of the electrocardiogram in LQTS. Both BS and LQTS can lead to syncope and even sudden death. The R1193Q SCN5A variant was recently associated with LQTS, BS and cardiac conductance disease. Objective and Methods The aim of the present study was to screen the SCN5A gene from two patients – one with BS and the other showing signs of a BS/LQTS phenotype – for mutations, and to characterize the effect of the mutations on channel function using the patch clamp technique. Results A heterozygous mutation (R1193Q) was identified on the SCN5A gene in both patients. The R1193Q polymorphism was absent in 100 unrelated control alleles, suggesting that it has a low frequency in the French Canadian population. Mutant R1193Q expressed in tsA201 cells, which was studied using the patch clamp technique, had a persistent sodium current that could account for the QTc prolongation. A shift of steady-state inactivation toward more hyperpolarized voltages was observed that could explain the BS phenotype. Conclusion The R1193Q polymorphism is definitively associated with cardiac electrical abnormalities.

Non-synonymous single nucleotide polymorphisms (SNPs) in the KCNA5/hKv1.5 gene, which encodes for a voltage-gated K+ channel responsible for the I Kur current in the human atria, have been recently reported. To gain further knowledge on potential influence of hKv1.5 SNPs, we searched for their presence in a specific population of 96 French-Canadians and characterized electrophysiological properties of the variants in two cell lines. The presumed promoter (−83 bp) and coding regions were sequenced. We found three heterozygous SNPs: R87Q, A251T, and P307S. Functional analysis of SNPs transfected in Chinese hamster ovary (CHO) cells showed that both R87Q and P307S diminished the inactivation amplitude (e.g., at +60 mV, amplitudes were 89±26, 23±4, and 22±7 pA/pF for the wild type, R87Q and P307S, respectively; n=8, 6, and 8, respectively). Inactivation was slowed with these variants (e.g., τ fast at +50 mV were 270±48, 490±66, and 340±45 ms for the wild type, R87Q, and P307S, respectively) while R87Q additionally accelerated the rate of hKv1.5 channel opening. A dominant-negative effect was observed for R87Q but not for P307S. SNPs properties were not reproduced when expressed in the HEK293 cell line, suggesting that the regulatory β-subunit present in CHO cells (and the human heart) is essential for the SNPs effects that we have observed.

Little is known about differences in practice patterns or outcomes in the management of patients who have atrial fibrillation in Canada compared with those in the United States (US). We evaluated the effect that the country of enrollment may have on the management patterns and clinical outcomes in patients who participated in the AFFIRM study. Three thousand four hundred patients came from the US and 660 from Canada. In the US, patients were more likely to have a history of coronary artery disease (39% vs 35%, p = 0.03), hypertension (72% vs 67%, p = 0.01), or congestive heart failure (24% vs 18%, p = 0.0002). More US participants were

CHAMPAGNE, J., et al.: Permanent Pacemaker Lead Entrapment: Role of the Transesophageal Echocardiography. Numerous complications induced by pacemaker electrodes have been reported. Although mild tricuspid regurgitation is a well-documented complication of transvenous right ventricular pacemaker leads secondary to abnormal valve coaptation, severe tricuspid regurgitation resulting from perforation of the tricuspid valve itself is a rare complication. This case report details a patient with severe tricuspid regurgitation secondary to impingement of the tricuspid valve by a permanent pacing lead that was diagnosed by transesophageal echocardiography. Surgical repair was advocated because of symptomatic significant tricuspid regurgitation.

Background: There is limited information regarding characteristics of patients with Brugada syndrome (BrS) who received a prophylactically implantable cardioverter-defibrillator (ICD) that delivered appropriate therapy. We sought to compare patients’ characteristics and indications of prophylactic

Background Cable externalization and insulation abrasion are known to occur with the St Jude Medical Riata leads under advisory. The distribution of these abnormalities and how they relate to clinical presentation have not been well described. Objective In this study, we sought to determine the relationship between structural lead failure and clinical presentation by using the analysis of returned Riata products in Canada. Methods The analyses of returned Riata products in Canada were obtained from St Jude Medical, Sylmar, CA. These data were correlated with the clinical presentation of patients just before lead removal from service. Results As of May 1, 2013, there were 263 returned Riata leads in Canada. Of these, 43 (16.8%) were found to have insulation abrasion that was due to either lead-can or lead-other device interaction (70%) or inside-out abrasion (27.9%). The predilection of lead-to-can abrasion was seen in the Riata 7-F leads (84.2% vs 58.4%; P = .07), while inside-out abrasion was more common in the Riata 8-F leads (37.5% vs 15.8%; P = .12). Electrical abnormalities were frequent (20 of 31 [65.4%]) and most often due to electrical noise (45.2%), although inappropriate shocks were present (25.8%). Death occurred in 1 of 43 (2.3%) of those patients with an insulation defect in the lead-can abrasion group. Conclusion Lead-can abrasion is the most common form of insulation defect in the Riata group of leads under advisory. Management of this group of leads under advisory should not neglect the issue of lead-can abrasion, in addition to detection of cable externalization.

Riata™ and Riata ST defibrillation leads (St. Jude Medical, Sylmar, CA, USA) are susceptible to insulation defects with conductor externalization. Cine-fluoroscopy is considered to be the gold standard for the documentation of insulation defects, but similar detection rates have been reported for posterior-anterior (PA)/lateral chest x-ray (CXR) with zooming.Prospective single-center study to assess the diagnostic equivalence of a PA/lateral CXR with zooming for the detection of Riata insulation defects in a direct comparison to cine-fluoroscopy.Seventy-eight consecutive patients underwent 3-view cine-fluoroscopy and a PA/lateral CXR. All CXRs and cine-fluoroscopy images were reviewed by blinded electrophysiologists and staff radiologists.Forty-four of 78 patients had an abnormal cine-fluoroscopy (56%). The diagnostic correlation between PA/lateral CXR and cine-fluoroscopy was excellent (κ = 0.90; 95% confidence interval 0.80-1.00). PA/lateral CXR was equivalent to cine-fluoroscopy for the detection of conductor externalization showing a sensitivity of 97.7% and a specificity of 91.2%. The mean radiation effective dose of CXR was significantly lower compared to cine-fluoroscopy (0.09 millisievert [mSV] vs 0.85 ± 0.47 mSv; P0.001). Also, CXR was significantly less expensive.PA/lateral CXR with zooming is equivalent to cine-fluoroscopy for the detection of Riata insulation defects and should be considered as the preferred screening method.

Atrial fibrillation (AF) is the most common rhythm disorder seen in clinical practice. Antiarrhythmic drugs are effective for reduction of recurrence in patients with symptomatic paroxysmal AF. Radiofrequency ablation is an accepted therapy in patients for whom antiarrhythmic drugs have failed; however, its role as a first-line therapy needs further investigation.To compare radiofrequency ablation with antiarrhythmic drugs (standard therapy) in treating patients with paroxysmal AF as a first-line therapy.A randomized clinical trial involving 127 treatment-naive patients with paroxysmal AF were randomized at 16 centers in Europe and North America to received either antiarrhythmic therapy or ablation. The first patient was enrolled July 27, 2006; the last patient, January 29, 2010. The last follow-up was February 16, 2012.Sixty-one patients in the antiarrhythmic drug group and 66 in the radiofrequency ablation group were followed up for 24 months.The time to the first documented atrial tachyarrhythmia of more than 30 seconds (symptomatic or asymptomatic AF, atrial flutter, or atrial tachycardia), detected by either scheduled or unscheduled electrocardiogram, Holter, transtelephonic monitor, or rhythm strip, was the primary outcome. Secondary outcomes included symptomatic recurrences of atrial tachyarrhythmias and quality of life measures assessed by the EQ-5D tool.Forty-four patients (72.1%) in the antiarrhythmic group and in 36 patients (54.5%) in the ablation group experienced the primary efficacy outcome (hazard ratio [HR], 0.56 [95% CI, 0.35-0.90]; P = .02). For the secondary outcomes, 59% in the drug group and 47% in the ablation group experienced the first recurrence of symptomatic AF, atrial flutter, atrial tachycardia (HR, 0.56 [95% CI, 0.33-0.95]; P = .03). No deaths or strokes were reported in either group; 4 cases of cardiac tamponade were reported in the ablation group. In the standard treatment group, 26 patients (43%) underwent ablation after 1-year. Quality of life was moderately impaired at baseline in both groups and improved at the 1 year follow-up. However, improvement was not significantly different among groups.Among patients with paroxysmal AF without previous antiarrhythmic drug treatment, radiofrequency ablation compared with antiarrhythmic drugs resulted in a lower rate of recurrent atrial tachyarrhythmias at 2 years. However, recurrence was frequent in both groups.clinicaltrials.gov Identifier: NCT00392054.

Background and objective Mexiletine and propafenone are often used concomitantly and are metabolized by the same cytochrome P450 isozymes, namely CYP2D6, CYP1A2, and probably CYP3A4. Our objective was to study the potential pharmacokinetic and electrophysiological interactions between mexiletine and propafenone. Methods Fifteen healthy volunteers, 8 extensive metabolizers and 7 poor metabolizers of CYP2D6, received oral doses of mexiletine 100 mg two times daily from day 1 to day 8 and oral doses of propafenone 150 mg two times daily from day 5 to day 12. Interdose studies were performed at steady-state on mexiletine alone (day 4), mexiletine plus propafenone (day 8), and propafenone alone (day 12). Results In subjects in the extensive metabolizer group, coadministration of propafenone decreased oral clearances of R-(−)-mexiletine (from 41 ± 11 L/h to 28 ± 7 L/h) and S-(+)-mexiletine (from 43 ± 15 L/h to 29 ± 11 L/h) to an extent such that these values were no longer different between the extensive and the poor metabolizer groups. Propafenone coadministration also decreased partial metabolic clearances of mexiletine to hydroxymethylmexiletine, p-hydroxymexiletine, and m-hydroxymexiletine in extensive metabolizers by 71%, 67%, and 73%, respectively. In contrast, propafenone did not alter the kinetics of mexiletine enantiomers in subjects in the poor metabolizer group except for a slight decrease in the formation of hydroxymethylmexiletine. Pharmacokinetic parameters of propafenone were not changed during concomitant administration of mexiletine in subjects of either phenotype. Finally, electrocardiographic parameters (QRS duration, QTc, RR, and PR intervals) were not modified during the combined administration of the drugs. Conclusion Propafenone is a potent CYP2D6 inhibitor that may cause an increase in plasma concentrations of coadministered CYP2D6 substrates. Clinical Pharmacology & Therapeutics (2000) 68, 44–57; doi: 10.1067/mcp.2000.108023

The Canadian Heart Rhythm Society (CHRS) Device Advisory Committee was commissioned to respond to advisories regarding cardiac rhythm device and lead performance on behalf of the CHRS. In the event of an advisory, the Chair uses an e-mail network to disseminate advisory information to Committee members broadly representative of the Canadian device community. A consensus recommendation is prepared by the Committee and made available to all Canadian centres on the CHRS Web site after approval by the CHRS executive. This collaborative approach using an e-mail network has proven very efficient in providing a rapid national response to device advisories. The network is an ideal tool to collect specific data on implanted device system performance and allows for prompt reporting of clinically relevant data to front-line clinicians and patients.

Background Provocative testing with sodium channel blockers is advocated for the evaluation of unexplained cardiac arrest (UCA) with the primary purpose of unmasking the typical ECG features of Brugada syndrome. The Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) systematically assesses subjects with UCA or a family history of sudden death (FHSD). Objective The purpose of this study was to determine the clinical yield of procainamide infusion in a national registry of subjects with either UCA or a FHSD. Methods Subjects with either UCA or a FHSD without evidence of a Brugada pattern at baseline underwent procainamide testing (15 mg/kg to a maximum of 1 g at 50 mg/min). A test was considered positive for Brugada pattern if there was an increase in ST elevation >1 mm or if there was >1 mm of new ST elevation in leads V1 and/or V2. Genetic testing was performed on the basis of phenotype detection. Results Procainamide testing was performed in 174 subjects (age 46.8 ± 15.4 years, 47% female). Testing provoked a Brugada pattern in 12 subjects (6.9%), 5 of whom had no ST abnormalities at baseline. No subjects with a negative procainamide challenge were subsequently diagnosed with Brugada syndrome. Genetic testing was conducted in 10 of the 12 subjects with a provoked Brugada pattern and was positive for a mutation in the SCN5A gene in 1. Conclusion Irrespective of the baseline ECG, procainamide testing provoked a Brugada pattern in a significant proportion of subjects with UCA or a FHSD, thereby facilitating a diagnosis of Brugada syndrome, and is recommended in the workup of UCA.

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.

Background Patients with Brugada syndrome (BrS) are at risk for ventricular arrhythmias (VAs) and sudden death. Identification of high-risk individuals beyond those with syncope or resuscitated sudden death remains a major challenge. Methods We assessed the value of clinical, electrophysiological, and electrocardiographic (ECG) features, including depolarization and repolarization metrics, in predicting arrhythmic events and sudden death in consecutive patients with BrS diagnosed between 2002 and 2013 in Quebec, Canada. Qualifying electrocardiograms with the highest type 1 ST-segment elevations were reviewed and analyzed by 2 electrophysiologists who were blinded to clinical history. Survival analyses were adjusted for Firth bias correction and left truncation. Results A total of 105 patients, 79.8% of whom were men, were diagnosed with BrS at a mean age of 46.2 ± 13.3 years and were followed for 59.6 ± 16.4 months. Ten (9.5%) had a history of cardiac arrest, 37 (35.2%) had syncope, and 7 (6.7%) experienced 20 arrhythmic events during follow-up, all consisting of appropriate ICD therapy (7 antitachycardia pacing; 13 shocks). In multivariate Cox regression analyses, a spontaneous type 1 electrocardiographic (ECG) pattern (hazard ratio [HR], 10.80; 95% confidence interval [CI], 1.03-113.87; P = 0.0476), maximal T peak-end (T p-e ) duration ≥ 100 ms (HR, 29.73; 95% CI, 1.33-666.37; P = 0.0325), and QRS duration in lead V 6 > 110 ms (HR, 15.27; 95% CI, 1.07-217.42; P = 0.0443) were independently associated with VAs or aborted sudden cardiac death. Conclusions In a multicentre cohort with BrS from Quebec, Canada, VAs and sudden death were independently associated with standard 12-lead ECG features, including a spontaneous type 1 pattern, depolarization (QRS in lead V 6 ), and repolarization (maximal T p-e duration) criteria.

Extra-anatomic Course of a Right Ventricular Pacing Lead: Clinical Implications Pierre-Louis Nadeau, MD, Jean Champagne, MD, Franck Molin, MD, Jean-Francois Sarrazin, MD, Gilles O’Hara, MD, Isabelle Nault, MD, Louis Blier, MD, Eric Charbonneau, MD, Fr ed eric Jacques, MD, and Francois Philippon, MD Electrophysiology Division, Institut universitaire de cardiologie et de pneumologie de Qu ebec, Laval University, Qu ebec City, Qu ebec, Canada Cardiac Surgery Division, Institut universitaire de cardiologie et de pneumologie de Qu ebec, Laval University, Qu ebec City, Qu ebec, Canada

Aims Insulation breaches with externalization of conductor cables have been described for St-Jude Medical Riata™ defibrillation leads. Published data on the incidence of Riata lead abnormalities are quite heterogeneous. The objective of this study was to estimate systematically the prevalence of lead abnormalities using a postero-anterior (PA) and lateral chest X-ray (CXR). Methods and results From 2002 to 2008, 552 Riata defibrillation leads were implanted at our centre. We evaluated patients for potential insulation breaches. A PA and lateral CXR was obtained. Chest X-rays were reviewed by two electrophysiologists using a zooming function with magnification up to factor 7.5 and were classified as normal or abnormal for the presence of conductor externalization. A total of 284 patients were included. Riata lead models were 1570, 1580, 1582, 1590, 1592, 7000, 7002, and 7022. The total frequency of radiological lead defects was 24.3%. Insulation breaches occurred at zones of major lead curvature. Mean maximal spacing between extruding lead components was 3.6 ± 1.9 mm (range 2.0–12.4). Abnormal CXRs were more frequent in 8F leads (31.4% vs. 6.3%; P < 0.001). Most defects occurred with lead models 1582 (41.2%) and 1580 (31.4%). Mean time since implantation was longer in abnormal leads (6.7 vs. 5.9 years; P < 0.001). Abnormal leads had higher pacing thresholds (1.1 ± 0.8 V vs. 0.9 ± 0.4 V; P = 0.02). Conclusion The incidence of insulation breach in Riata leads is much higher than quoted by the manufacturer or reported by most of the literature. A PA and lateral CXR with zooming appears adequate to identify lead breaches when reviewed by an electrophysiologist. Riata lead breaches without electrical abnormalities present a management dilemma and will require further studies.

Poor R‐wave progression (PRWP) in the precordial leads on random ECG is relatively frequent in the general population and includes a broad differential diagnosis. Here, we present for the first time a case of complete absence of precordial R waves associated with a prominent R wave in aVR due to the absence of the left‐sided pericardium in a 44‐year‐old woman who experienced sudden cardiac death.

Background— Epinephrine infusion may unmask latent genetic conditions associated with cardiac arrest, including long-QT syndrome and catecholaminergic polymorphic ventricular tachycardia (VT). Methods and Results— Patients with unexplained cardiac arrest (normal left ventricular function and QT interval) and selected family members from the Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) registry underwent epinephrine challenge at doses of 0.05, 0.10, and 0.20 μg/kg per minute. A test was considered positive for long-QT syndrome if the absolute QT interval prolonged by ≥30 ms at 0.10 μg/kg per minute and borderline if QT prolongation was 1 to 29 ms. Catecholaminergic polymorphic VT was diagnosed if epinephrine provoked ≥3 beats of polymorphic or bidirectional VT and borderline if polymorphic couplets, premature ventricular contractions, or nonsustained monomorphic VT was induced. Epinephrine infusion was performed in 170 patients (age, 42±16 years; 49% men), including 98 patients with unexplained cardiac arrest. Testing was positive for long-QT syndrome in 31 patients (18%) and borderline in 24 patients (14%). Exercise testing provoked an abnormal QT response in 42% of tested patients with a positive epinephrine response. Testing for catecholaminergic polymorphic VT was positive in 7% and borderline in 5%. Targeted genetic testing of abnormal patients was positive in 17% of long-QT syndrome patients and 13% of catecholaminergic polymorphic VT patients. Conclusions— Epinephrine challenge provoked abnormalities in a substantial proportion of patients, most commonly a prolonged QT interval. Exercise and genetic testing replicated the diagnosis suggested by the epinephrine response in a small proportion of patients. Epinephrine infusion combined with exercise testing and targeted genetic testing is recommended in the workup of suspected familial sudden death syndromes. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00292032.

This study sought to assess the safety and effectiveness of a novel cryoballoon ablation technology designed to achieve single-delivery pulmonary vein (PV) isolation.Standard radiofrequency ablation is effective in eliminating atrial fibrillation (AF) but requires multiple lesion delivery at the risk of significant complications.Patients with documented symptomatic paroxysmal AF and previously failed therapy with ≥ 1 membrane active antiarrhythmic drug underwent 2:1 randomization to either cryoballoon ablation (n = 163) or drug therapy (n = 82). A 90-day blanking period allowed for optimization of antiarrhythmic drug therapy and reablation if necessary. Effectiveness of the cryoablation procedure versus drug therapy was determined at 12 months.Patients had highly symptomatic AF (78% paroxysmal, 22% early persistent) and experienced failure of at least one antiarrhythmic drug. Cryoablation produced acute isolation of three or more PVs in 98.2% and all four PVs in 97.6% of patients. PVs isolation was achieved with the balloon catheter alone in 83%. At 12 months, treatment success was 69.9% (114 of 163) of cryoblation patients compared with 7.3% of antiarrhythmic drug patients (absolute difference, 62.6% [p0.001]). Sixty-five (79%) drug-treated patients crossed over to cryoablation during 12 months of study follow-up due to recurrent, symptomatic AF, constituting drug treatment failure. There were 7 of the resulting 228 cryoablated patients (3.1%) with a75% reduction in PV area during 12 months of follow-up. Twenty-nine of 259 procedures (11.2%) were associated with phrenic nerve palsy as determined by radiographic screening; 25 of these had resolved by 12 months. Cryoablation patients had significantly improved symptoms at 12 months.The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF, for whom at least one antiarrhythmic drug has failed, with risks within accepted standards for ablation therapy. (A Clinical Study of the Arctic Front Cryoablation Balloon for the Treatment of Paroxysmal Atrial Fibrillation [Stop AF]; NCT00523978).

Congenital absence of the pericardium is a very rare cardiac malformation, usually diagnosed fortuitously on autopsy or surgery. Symptoms related to these abnormalities are usually benign, and fatalities reported in the literature are almost exclusively secondary to herniation of the heart through a partial defect. We present the unusual case of a 44-year-old woman admitted for sudden cardiac arrest. Initial evaluation suggested acute anterior myocardial infarction, but further investigation ruled out coronary heart disease. No arrhythmia could be initiated on electrophysiological study, and absence of most of the left pericardium was confirmed by cardiac magnetic resonance imaging. After the exclusion of common etiologies such as idiopathic ventricular fibrillation, transient great vessel torsion due to hypermobility of the heart with secondary malignant arrhythmia was considered to be the most likely mechanism for the sudden cardiac arrest. A review of the available literature on clinical presentation, diagnostic tools, and therapeutic options is also presented.