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Atrial low voltage area (LVA) catheter ablation has emerged as a promising strategy for ablation of persistent atrial fibrillation (AF). It is unclear if catheter ablation of atrial LVA increases treatment success rates in patients with persistent AF.The primary aim of this trial is to assess the potential benefit of adjunctive catheter ablation of atrial LVA in addition to pulmonary vein isolation (PVI) in patients with persistent AF, when compared to PVI alone. The secondary aims are to evaluate safety outcomes, the quality of life and the healthcare resource utilization.A multicenter, prospective, parallel-group, 2-arm, single-blinded randomized controlled trial is under way (NCT03347227). Patients who are candidates for catheter ablation for persistent AF will be randomly assigned (1:1) to either PVI alone or PVI + atrial LVA ablation. The primary outcome is 18-month documented event rate of atrial arrhythmia (AF, atrial tachycardia or atrial flutter) post catheter ablation. Secondary outcomes include procedure-related complications, freedom from atrial arrhythmia at 12 months, AF burden, need for emergency department visits/hospitalization, need for repeat ablation for atrial arrhythmia, quality of life at 12 and 18 months, ablation time, and procedure duration.Characterization of Arrhythmia Mechanism to Ablate Atrial Fibrillation (COAST-AF) is a multicenter randomized trial evaluating ablation strategies for catheter ablation. We hypothesize that catheter ablation of atrial LVA in addition to PVI will result in higher procedural success rates when compared to PVI alone in patients with persistent AF.

The Medical Assistance in Dying (MAiD) program has been steadily expanding in Canada, and is expected to continue to do so. There are a substantial number of Canadians with pacemakers and defibrillators, many of whom are potential MAiD recipients. There is a need for review and reflection of standardisation of cardiac device management in MAiD patients, not only because of ethical concerns, but also because of the complexity of management at end of life. This document examines the status and role of cardiac devices (pacemakers and intracardiac defibrillators) and their physiologic interactions and influences during the MAiD process, and provides recommendations for their management.

Background Decision support can help patients facing implantable cardioverter-defibrillator (ICD) replacement understand their options and reach an informed decision reflective of their preferences. Objective The aim of this study was to evaluate the feasibility of a decision support intervention for patients faced with the decision to replace their ICD. Methods A pilot feasibility randomized trial was conducted. Patients approaching ICD battery depletion were randomized to decision support intervention or usual care. Feasibility outcomes included recruitment rates, intervention use, and completeness of data; secondary outcomes were knowledge, values-choice concordance, decisional conflict, involvement in decision making, and choice. Results A total of 30 patients were randomized to intervention (n = 15) or usual care (n = 15). The intervention was used as intended, with 2% missing data. Patients in the intervention arm had better knowledge (77.4% vs 51.1%; P = .002). By 12 months, 8 of 13 (61.5%) in the intervention arm and 10 of 14 (71.4%) in the usual care arm accepted ICD replacement; 1 per arm declined (7.7% vs 7.1%, respectively). Conclusion It was feasible to deliver the intervention, collect data, despite slow recruitment. The decision support intervention has the potential to improve ICD replacement decision quality.

Several approaches have been proposed to address the challenge of catheter ablation of persistent atrial fibrillation (AF). However, the optimal ablation strategy is unknown. We sought to evaluate the efficacy of pulmonary vein isolation (PVI) plus low-voltage area (LVA) ablation using contemporary high-density mapping to identify LVA in patients with persistent AF.Consecutive patients accepted for AF catheter ablation were studied. High-density bipolar voltage mapping data were acquired in sinus rhythm using multipolar catheters to detect LVA (defined as bipolar voltage0.5 mV). Semiautomated impedance-based software was used to ensure catheter contact during data collection. Patients underwent PVI + LVA ablation (if LVA present).A total of 145 patients were studied; 95 patients undergoing PVI + LVA ablation were compared with 50 controls treated with PVI only. Average age was 61 ± 10 years, and 80% were male. Baseline characteristics were comparable. Freedom from atrial tachycardia/AF at 18 months was 72% after PVI + LVA ablation vs 58% in controls (P = 0.022). Median procedure duration (273 [240, 342] vs 305 [262, 360] minutes; P = 0.019) and radiofrequency delivery (50 [43, 63] vs 55 [35, 68] minutes; P = 0.39) were longer in the PVI + LVA ablation group. Multivariable analysis showed that the ablation strategy (PVI + LVA) was the only independent predictor of freedom from atrial tachycardia/AF (hazard ratio, 0.53; 95% confidence interval, 0.29-0.96; P = 0.036). There were no adverse safety outcomes associated with LVA ablation.An individualized strategy of high-density mapping to assess the atrial substrate followed by PVI combined with LVA ablation is associated with improved outcomes. Adequately powered randomized clinical trials are needed to determine the role of PVI + LVA ablation for persistent AF.

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%, P = 0.033). Routine TEE strategy yielded a lower LAAT prevalence in both groups (0.1% vs 2.3%, P = 0.002 and 3.2% vs 5.8%, P = 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. Résumé: Introduction: De nombreuses études ont porté sur la prévalence des thrombi se formant dans l’appendice auriculaire gauche (TAAG) chez les patients qui reçoivent des anticoagulants oraux directs (AOD) et ont révélé des résultats contradictoires. Méthodes: Nous avons recensé les études qui ont fait état de la prévalence des TAAG à l’échocardiographie transœsophagienne (ETO) trois semaines ou plus après le traitement par AOD. Les modèles à effets aléatoires ont permis de regrouper les patients qui prenaient des anticoagulants et avaient reçu un diagnostic de TAAG. Nous avons réalisé les analyses de sous-groupes prédéterminés par l’indication d’ETO (fibrillation auriculaire [FA] avant l’ablation vs FA avant la cardioversion) et la stratégie d’utilisation de l’ETO (systématique vs sélective) grâce à la stratification. Résultats: Nous avons recensé 40 études : 22 manuscrits complets et 18 résumés. Seules 11 études portaient sur l’utilisation systématique de l’ETO. La plupart des études portaient sur des patients qui étaient atteints de FA paroxystique et exposés à un faible risque thromboembolique. La prévalence groupée de TAAG était de 2,5 % (intervalle de confiance à 95 % [1,6 %-3,4 %]). La prévalence de TAAG était plus faible dans le groupe de FA avant l’ablation que dans le groupe de FA avant la cardioversion (1,1 % vs 4,0 %, P = 0,033). La stratégie d’utilisation systématique de l’ETO a permis d’obtenir une prévalence plus faible de TAAG dans les deux groupes (0,1 % vs 2,3 %, P = 0,002 et 3,2 % vs 5,8 %, P = 0,432, respectivement). Conclusion: La prévalence de TAAG à l’ETO chez les patients traités par AOD varie beaucoup. Les facteurs associés à une prévalence élevée de TAAG étaient l’indication avant la cardioversion et la stratégie d’utilisation sélective de l’ETO. L’utilisation systématique de l’ETO avant l’ablation peut ne pas être justifiée.

Background QT interval monitoring has gained much interest during the COVID-19 pandemic given the use of QT-prolonging medications and the concern about viral transmission with serial 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 episodes (Long-QTc), 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 (EP-QTc) 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%), P < 0.0001] and ECGs were performed less frequently [32/206 (16%) vs 78/245 (32%), P < 0.0001]. Auto-QTc correlated well with EP-QTc with an excellent agreement in detecting Long-QTc (Kappa=0.8, P, Brief Summary In this prospective cohort study of consecutive patients admitted with suspected or confirmed COVID-19, we found that continuous QT monitoring was associated with improvement in the detection of markedly prolonged QTc episodes (QTc > 500 ms) and less use of ECGs, as compared to standard of care. Also, we found that most episodes of hospital acquired prolonged QTc episodes were not treated according to recommendations.

ImportanceRecurrent atrial fibrillation (AF) commonly occurs after catheter ablation and is associated with patient morbidity and health care costs.ObjectiveTo evaluate the superiority of an augmented double wide-area circumferential ablation (WACA) compared with a standard single WACA in preventing recurrent atrial arrhythmias (AA) (atrial tachycardia, atrial flutter, or atrial fibrillation [AF]) in patients with paroxysmal AF.Design, Setting, and ParticipantsThis was a pragmatic, multicenter, prospective, randomized, open, blinded end point superiority clinical trial conducted at 10 university-affiliated centers in Canada. The trial enrolled patients 18 years and older with symptomatic paroxysmal AF from March 2015 to May 2017. Analysis took place between January and April 2022. Analyses were intention to treat.InterventionsPatients were randomized (1:1) to receive radiofrequency catheter ablation for pulmonary vein isolation with either a standard single WACA or an augmented double WACA.Main Outcomes and MeasuresThe primary outcome was AA recurrence between 91 and 365 days postablation. Patients underwent 42 days of ambulatory electrocardiography monitoring after ablation. Secondary outcomes included need for repeated catheter ablation and procedural and safety variables.ResultsOf 398 patients, 195 were randomized to the single WACA (control) arm (mean [SD] age, 60.6 [9.3] years; 65 [33.3%] female) and 203 to the double WACA (experimental) arm (mean [SD] age, 61.5 [9.3] years; 66 [32.5%] female). Overall, 52 patients (26.7%) in the single WACA arm and 50 patients (24.6%) in the double WACA arm had recurrent AA at 1 year (relative risk, 0.92; 95% CI, 0.66-1.29; P = .64). Twenty patients (10.3%) in the single WACA arm and 15 patients (7.4%) in the double WACA arm underwent repeated catheter ablation (relative risk, 0.72; 95% CI, 0.38-1.36). Adjudicated serious adverse events occurred in 13 patients (6.7%) in the single WACA arm and 14 patients (6.9%) in the double WACA arm.Conclusions and RelevanceIn this randomized clinical trial of patients with paroxysmal AF, additional ablation by performing a double ablation lesion set did not result in improved freedom from recurrent AA compared with a standard single ablation set.Trial RegistrationClinicalTrials.gov Identifier: NCT02150902

The rhythm-monitoring strategy after catheter ablation (CA) for atrial fibrillation (AF) impacts the detection of atrial arrhythmia recurrence and is not well characterized. We performed a systematic review and meta-regression analysis to determine whether the duration and mode of rhythm monitoring after CA affects detection of atrial arrhythmia recurrence.Databases were systematically searched for randomized controlled trials of adult patients undergoing first CA for AF from 2007 to 2021. Duration and strategy of rhythm monitoring were extracted. Meta-regression was used to identify any association between duration of monitoring and detection of atrial arrhythmia recurrence. The primary measure of outcome was single-procedure recurrence of atrial arrhythmia.The search strategy yielded 57 trial arms from 56 randomized controlled trials comprising 5322 patients: 36 arms of patients with paroxysmal AF (PAF), and 21 arms of patients with persistent AF (PeAF) or both PAF/PeAF. Intermittent monitoring was associated with detection of significantly less atrial arrhythmia recurrence than continuous monitoring in PAF arms (31.2% vs 46.9%,Continuous rhythm monitoring detected higher atrial arrhythmia recurrence rates, compared to intermittent rhythm monitoring, in patients with PAF. The duration of intermittent monitoring did not show a statistically significant relationship to the yield of arrhythmia detection, in near identical cohorts of trial subjects undergoing similar interventions, with clinical and research implications.La stratégie qui consiste à surveiller le rythme cardiaque après une ablation par cathéter dans le traitement de la fibrillation auriculaire (FA) a un effet sur la détection de récidive de l’arythmie auriculaire, mais elle n’est pas bien définie. Nous avons mené une revue systématique et une méta-régression pour déterminer si le mode employé pour surveiller le rythme après une ablation par cathéter et la durée de cette surveillance ont un effet sur la détection de récidive de l’arythmie auriculaire.Des bases de données ont été systématiquement épluchées à la recherche d’essais contrôlés randomisés menés auprès d’adultes subissant leur première ablation par cathéter pour une FA entre 2007 et 2021. La durée et la stratégie utilisées dans la surveillance du rythme ont été recensées. La méta-régression a été utilisée pour déceler tout lien entre la durée de la surveillance et la détection d’une récidive de l’arythmie auriculaire. Le paramètre d’évaluation principal était la récidive de l’arythmie auriculaire avec une seule intervention.La stratégie de recherche a fait ressortir 57 groupes de 56 essais contrôlés randomisés comprenant 5 322 patients : 36 groupes de patients présentant une FA paroxystique et 21 groupes de patients présentant une FA persistante ou ces deux types de FA (paroxystique et persistante). La surveillance intermittente a été associée à une moins grande détection de cas d’arythmie auriculaire récidivante, comparativement à la surveillance constante (31,2 % vs 46,9 %,Le taux de détection de l’arythmie auriculaire récidivante était plus élevé avec la surveillance constante qu’avec la surveillance intermittente chez les patients atteints de FA paroxystique. La durée de la surveillance intermittente n’a pas eu de lien statistiquement significatif avec le rendement de détection de l’arythmie, dans des cohortes presque identiques de participants aux essais subissant des interventions similaires, comportant des implications cliniques ou expérimentales.

Introduction: Reduced BDNF concentrations have been observed in patients with depression and heart failure, with treatment and improvement in symptoms associated with increased concentrations. AF is associated with symptoms of depression and poor Quality of Life (QoL). Hypothesis: We hypothesized that patients without AF recurrence following catheter ablation would have higher BDNF concentrations, less depression severity, and improved QoL scores. Methods: A prospective observational study was conducted. BDNF (biosensis® Rapid ™ ELISA) concentrations were performed and the Beck Depression Inventory-II (BDI-II), Short Form-36 Health Survey (SF-36) and AF Severity Scale (AFSS) were administered before and 12 weeks after catheter ablation. The primary outcome was change in BDNF blood concentrations following catheter ablation and its relationship with depression severity and AF related QoL. Results: One hundred patients with paroxysmal AF were recruited of which 98 completed the study. Eighty-nine patients were free of recurrent AF/atrial arrhythmias (AA) following catheter ablation. The baseline demographics and results are summarized in the accompanying table. Statistically significant changes were observed in BDNF concentrations, BDI scores and AFSS (perceived AF burden and symptoms) in patients without AF recurrence, after adjustments for CHADS2 score, age, and sex. The number of patients with AF recurrence were too few to make meaningful interpretation of results. Conclusions: BDNF concentrations significantly improved in subjects without AF recurrence after catheter ablation and were associated with a concomitant reduction in depression severity, perceived AF burden and symptoms of paroxysmal AF. Further research is required to determine the mechanism(s) that explain this novel association between BDNF and AF related symptoms.

Recurrence of atrial fibrillation (AF) after a pulmonary vein isolation procedure is often due to electrical reconnection of the pulmonary veins. Repeat ablation procedures may improve freedom from AF but are associated with increased risks and health care costs. A novel ablation strategy in which patients receive "augmented" ablation lesions has the potential to reduce the risk of AF recurrence.The Augmented Wide Area Circumferential Catheter Ablation for Reduction of Atrial Fibrillation Recurrence (AWARE) Trial was designed to evaluate whether an augmented wide-area circumferential antral (WACA) ablation strategy will result in fewer atrial arrhythmia recurrences in patients with symptomatic paroxysmal AF, compared with a conventional WACA strategy.The AWARE trial was a multicenter, prospective, randomized, open, blinded endpoint trial that has completed recruitment (ClinicalTrials.gov NCT02150902). Patients were randomly assigned (1:1) to either the control arm (single WACAlesion set) or the interventional arm (augmented- double WACA lesion set performed after the initial WACA). The primary outcome was atrial tachyarrhythmia (AA; atrial tachycardia [AT], atrial flutter [AFl] or AF) recurrence between days 91 and 365 post catheter ablation. Patient follow-up included 14-day continuous ambulatory ECG monitoring at 3, 6, and 12 months after catheter ablation. Three questionnaires were administered during the trial- the EuroQuol-5D (EQ-5D) quality of life scale, the Canadian Cardiovascular Society Severity of Atrial Fibrillation scale, and a patient satisfaction scale.The AWARE trial was designed to evaluate whether a novel approach to catheter ablation reduced the risk of AA recurrence in patients with symptomatic paroxysmal AF.

BACKGROUND Cardiac implantable electronic devices (CIEDs) usually require the use of transvenous leads. A long-term complication of this can be venous system occlusion. This can preclude insertion of new transvenous leads, which is usually required to upgrade a device or supplant a defective lead; these patients require a new CIED system to be implanted on the contralateral side. Removal of the pre-existing device and/or leads carries substantial risks, including procedural complications and infection. An alternative is to leave the old device in-situ ("abandoned") with appropriate programming to minimize interaction. However, there is limited long term information about the safety and potential interaction between devices. METHODS AND RESULTS We identified 12045 patients who underwent CIED implant and had a CXR post-procedure at the Ottawa Heart Institute between December 1998 and September 2020. We used an artificial intelligence-based algorithm to identify all patients who had radiographic evidence of more than one CIED system. Our study cohort consisted of 17 patients. The average age was 66.7 ± 14.6 years; 3 (18%) were female. The average PADIT score was 8.2 ± 1.6, corresponding to a >3% annual risk of hospitalization for CIED infection with intervention on the pre-existing device pocket. The average time between the abandoned and new device implant was 4.9 ± 3.3 years. The abandoned device was a pacemaker in 13 (77%), and a defibrillator in 4 (24%). The new device was a pacemaker in 2 (12%) and defibrillator in 15 (88%). The most common indication for contralateral placement was occluded veins, in 14 (82%) patients. Follow up was 3.7 ± 3.5 years; over this time, 6 patients had end-of-life reached on the abandoned device; device output was set to minimal voltage and pulse width. Three were Medtronic pacemakers that self-reverted to VVI 65. This caused interference with a CRT in one patient, necessitating explant of the abandoned device. In the second patient, the new device was programmed at VOO 80bpm to overcome the abandoned device. In the last patient, the abandoned device did not capture the myocardium at minimal output settings. In the remainder of the patients, no device interference was found; one additional patient had abandoned CIED removed for discomfort. CONCLUSION We found that abandoning devices is feasible and safe in the long-term, and can be used to avoid the risks incurred by device explant. Careful attention should be paid to end-of-life behaviour of certain abandoned devices and necessary programming to prevent interaction.

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

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.

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

Introduction Fluoroscopy use during catheter ablation procedures increases the cumulative lifetime radiation exposure of patients and operators, potentially leading to a higher risk of cancer and radiation-related injuries. Nonfluoroscopic ablation (NFA) has been described for supraventricular tachycardia, typical atrial flutter, paroxysmal atrial fibrillation (AF), and outflow-tract ventricular tachycardia (VT). Complete transition to NFA of more complex arrhythmias, including persistent AF, left atrial (LA) flutter, and structural VT, has not been previously described. We describe the transition to completely NFA of complex arrhythmias, including LA flutter and structural VT. The techniques, challenges, limitations, and results are described. Methods and results Complex ablation procedures were performed using intracardiac echocardiography (ICE) and a three-dimensional mapping system without fluoroscopy or lead protection. Eighty consecutive patients underwent NFA (mean age, 60.1 ± 9.9 years, 70 with LA arrhythmias, 10 with VT). All cases were performed without the need for rescue fluoroscopy. There was an initial increase in procedural time for ablation of LA arrhythmias upon transitioning to NFA. However, after excluding the first 20 NFA cases to allow for operator learning, the transition to NFA was not associated with an increase in mean procedural time (229 ± 38 vs 225 ± 32 minutes; P = 0.002 for noninferiority). All procedures were completed successfully with no complications. Conclusions NFA of most complex arrhythmias (persistent AF, LA flutter, and structural VT) is feasible, with a modest learning curve and no increase in procedural times.

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 2 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 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.

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.

BACKGROUND Cardiovascular implantable electronic devices (CIED) infection is associated with significant morbidity and devastating sequelae for the patients. The use of incremental perioperative antibiotics, as well as use of an antibiotic impregnated pouch to reduce periprocedural device infections have recently been investigated. Trials investigating these additive interventions have shown only modest benefit, in addition these interventions carry a high cost to the system. Cost of antibiotic pouches can be greater than $1000 per use and use of additive antibiotics in all comers was shown to be neutral in Canadian centers. We sought to determine the effect of skin barrier use at reducing the risk of CIED infection as a simple, low cost intervention at time of device implantation. METHODS AND RESULTS We conducted an audit of all CIED implant procedures completed between Jan 2007 and April 2020 by 17 experienced operators in a shared procedure practice model. All device infections requiring reoperation or extraction were collected prospectively and diagnosis reconfirmed by an infectious disease specialist. A skin barrier was used as per physician preference and operations were retrospectively evaluated for use of skin barrier. Antibiotic use and periprocedural care were consistent in all procedures as per institutional protocol. Over a 13-year period 14,607 procedures were completed (mean age 72 +/- 14 years, female 35%). A total of 7816 pacemakers, 3292 ICDs, 1482 CRTs, and 1635 device upgrade or lead revision procedures were performed. 3913 procedures were completed with skin barrier and 10693 without. There were 90 infections in the no barrier group vs. 19 infections in the barrier group (0.84% vs. 0.48%, p=0.02). After a sensitivity analysis adjusting for the number of procedures, procedure type (ILR, PPM, ICD, CRT, de novo vs. upgrade vs. revision vs. generator replacement), the difference remained statistically significant. CONCLUSION Our data suggests that skin barrier use may be protective against infection. Considering low cost of skin barrier and catastrophic sequelae of device infection, the use of skin barrier during the procedure may be considered as an additional preventative measure to reduce device related infection. The low rates of infection in the barrier group are likely due to operator experience, use of standardized guideline directed perioperative care, and likely reduction of skin flora translocation during the procedure. Re-evaluation after transition to use of skin barrier for all cases will help further confirm these findings.

BACKGROUND Recurrence of atrial fibrillation (AF) post-ablation occurs in 30-50% of patients. The approach to a repeat ablation, beyond isolation of reconnected pulmonary veins (PVs), is not well established. We sought to prospectively assess outcomes and determine predictors of recurrence among consecutive patients who underwent repeat AF ablation with a standardized approach. METHODS AND RESULTS This was a single-center prospective study of consecutive patients who underwent repeat AF ablation. Our ablation protocol consisted of six steps: PV re-isolation, ablation of left atrial low-voltage areas (LVAs), ablation of isoprenaline induced non-PV triggers, electrophysiology study (EPS), and ablation of all clinical and induced atrial flutters. Between February 2017 and January 2020, 725 AF ablations were performed at our center. Of these, 74 were repeat AF ablation using the new protocol. The average age was 62.5 ± 9.2 years; 18% were female; 51% had paroxysmal AF at time of initial ablation. The indication for repeat ablation was paroxysmal AF in 39 (53%) patients, persistent AF in 24 (32%) patients. Among the study cohort of 74 patients undergoing repeat AF ablation, 53 (72%) had PV reconnection; 30 (41%) had LVA; 7 (10%) had non-PV triggers; five (7%) had AVNRT, and five (7%) had typical atrial flutter. Arrhythmia-free survival was 65% at one year. The absence of PV reconnection was the only factor independently associated with recurrence (overall rate 71%, adjusted OR 7.91, 95% CI 2.31-27.16, p=0.001). The arrhythmia-free survival was 29% in those without PV reconnection; meanwhile it was 88% in those with all PVs reconnected. Those with absence of reconnection had more LVA (67% vs 30%, p=0.004) and hypertension (67% vs 30%, p=0.004), suggesting more atrial myopathy. CONCLUSION We describe a comprehensive approach to repeat AF ablation using a standardized protocol that included isolation of reconnected PVs, targeting all areas of low-voltage, ablating all non-PV triggers, inducible SVT, and atrial flutters. Finding reconnected PVs at repeat procedure was a strong predictor of arrhythmia-free survival. Recurrence rates were high among those with absence of PV reconnection, potentially suggesting advanced atrial substrate as the underlying etiology. Our findings demonstrate that PV re-isolation remains the most important treatable cause of atrial arrhythmia recurrence after AF ablation; however further research is needed to investigate therapies beyond PV re-isolation.

Introduction Targeting localized drivers (electrical rotors or focal impulses) during catheter ablation for atrial fibrillation (AF) has been proposed as a strategy to improve procedural success. However, the strength and quality of the evidence to support this approach is unclear. Methods and results Clinical studies reporting efficacy or safety outcomes of driver-guided ablation for AF were identified in Medline, Embase, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, Pubmed, and conference abstracts from major scientific meetings. Random-effects meta-analysis of efficacy outcomes from controlled studies was performed. Thirty-one reports from 30 studies were included: two randomized controlled trials, five nonrandomized controlled studies, and 23 uncontrolled studies. In controlled studies, driver-guided ablation has been associated with higher rates of acute AF termination (RR 2.08, 95% CI 1.43–3.05; P < 0.001) and increased freedom from AF/atrial tachycardia (AT) at ≥1 year (RR 1.34, 95% CI 1.05–1.70; P = 0.02). Similar rates of procedural complications have been reported between ablation strategies. Overall, current data on driver-guided ablation are predominantly from nonrandomized studies with considerable heterogeneity in mapping and ablation strategies used and in clinical outcomes reported. Conclusion Pooled data on the efficacy of AF driver-guided catheter ablation suggest increased freedom from AF/AT relative to conventional strategies. However, most studies are nonrandomized and of moderate quality. Though promising data exist, there remains no conclusive evidence for the efficacy of AF driver ablation. Robust data from randomized trials are needed.

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

Background: The World-wide Randomized Antibiotic Envelope Infection Prevention trial reported a 40% reduction in major cardiac implantable electronic device (CIED) infections within 12 months of the procedure with the use of an antibacterial-eluting envelope (TYRX Absorbable Antibacterial Envelope, Medtronic, Mounds View, MN). Objective: The purpose of this report was to describe the longer-term (>12 months) envelope effects on infection reduction and complications. Methods: All trial patients who underwent CIED replacement, upgrade, revision, or initial cardiac resynchronization therapy – defibrillator implantation received standard-of-care infection prophylaxis and were randomized in a 1:1 ratio to receive the envelope or not. CIED infection incidence and procedure and system-related complications were characterized through all follow-up (36 months) by using Cox proportional hazards regression modeling. Results: In total, 6800 patients received their intended randomized treatment (3371 envelope; 3429 control; mean follow-up period 21.0 ± 8.3 months). Major CIED-related infections occurred in 32 envelope patients and 51 control patients (Kaplan-Meier [KM] estimate 1.3% vs 1.9%; hazard ratio [HR] 0.64; 95% confidence interval [CI] 0.41–0.99; P = .046). Any CIED-related infection occurred in 57 envelope patients and 84 control patients (KM estimate 2.1% vs 2.8%; HR 0.69; 95% CI 0.49–0.97; P = .030). System- or procedure-related complications occurred in 235 envelope patients and 252 control patients (KM estimate 8.0% vs 8.2%; HR 0.95; 95% CI 0.79–1.13; P < .001 for noninferiority); the most common were lead dislodgment (1.1%), device lead damage (0.5%), and implant site hematoma (0.4%). Implant site pain occurred less frequently in the envelope group (0.1% vs 0.4%; P = .067). There were no (0.0%) reports of allergic reactions to the components of the envelope (mesh, polymer, or antibiotics). Conclusion: The effects of the TYRX envelope on the reduction of the risk of CIED infection are sustained beyond the first year postprocedure, without an increased risk of complications.

Background Defibrillator placement carries an inherent risk to the patient. Traditionally, major adverse events defined as cardiac arrest, tamponnade, pneumothorax, infection requiring re-operation, MI and CVA within 30 days are reported to occur between 3 and 4%. Minor complications such as heamatomae or lead dislodgement are reported between 8 and 13%. Novel lead technologies, protocolised programming and reduced use of Heparin bridging have been reported to reduce adverse outcomes. However, patients are still typically monitored in hospital for 24 hours to mitigate these risks. There is little evidence that discharge delay is effective yet incurs significant additional costs. Purpose We sought to evaluate the frequency and timing of adverse events relating to defibrillator surgery (ICD and CRT-D) at a large Canadian tertiary care center (UOHI). Methods We retrospectively reviewed all patients who received a defibrillator placed from 1st April 2013 to 31st March 2018 inclusive. Patient comorbidities were extracted from the hospital electronic medical record (EMR) system. Device related information and complications were extracted from UOHI PaceartTM system and EMR and cross referenced with physician remuneration databases. Results A total of 2221 procedures were performed on 2153 patients (78% male, mean age 65 years). The majority (60%) of defibrillator implants were de novo, with 884 (40%) pulse generator replacements/ upgrades and 868 (39%) defibrillators had CRT capability. Patients were routinely discharged within 24 hours of ICD surgery. Post-operative follow up ≥30 days was complete in 97% patients. Major adverse events occurred within 30 days in 9 patients (0.4%); 9 (100%) were infection requiring re-operation. An additional 32 patients (1.5%) required repeat interventions or readmission within 30 days of implant, most commonly due to lead dislodgement. Only 2 patients required readmission within 24 hours of surgery (0.1%). All procedure-related adverse events during clinical follow up (≤5 years) were 131 (5.9%) occurring in 122 patients. There were no apparent predictors of adverse events in this cohort. Conclusion(s) Contemporary risks to patients undergoing defibrillator surgery are considerably lower than that reported in 2010. The risk of infection appears constant despite increased antibiosis. Patients receiving an ICD or CRT-D can safely be discharged within 24 hours if no complications are apparent. Acknowledgement/Funding None

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.

Pulmonary vein reconnection leading to recurrence of atrial arrhythmias after pulmonary vein isolation (PVI) for atrial fibrillation remains a significant challenge. A number of adjunctive measures during PVI have been used to attempt to reduce pulmonary vein reconnection and recurrence of atrial arrhythmias. We performed a systematic review of the literature and meta-analysis of studies evaluating the efficacy of adjunctive measures used during PVI in reducing recurrent atrial arrhythmias.Our literature search found four interventions that met the prespecified definition of adjunctive measure: adenosine testing post-PVI, contact force-guided PVI, pacing inexcitability of the ablation line during PVI and additional ablation based on the computed tomography thickness of the pulmonary vein-left atrial appendage ridge. Sixteen studies enrolling 3507 patients met all inclusion and exclusion criteria. PVI performed with adjunctive measures was shown to reduce the 1-year recurrence rate of atrial arrhythmias. The point estimate for the combined relative risk of atrial arrhythmia recurrence was 0.56 [95% confidence interval (CI): 0.43-0.73; P value0.001] in the PVI with adjunctive measures group.PVI for atrial fibrillation assisted by adjunctive measures results in clinically significant reduction of recurrent atrial arrhythmias. Additional research is required to assess the relative efficacy of individual or combined adjunctive strategies used during PVI for atrial fibrillation.

Percutaneous catheter ablation can be an effective treatment for paroxysmal atrial fibrillation. However, catheter ablation for the treatment of persistent atrial fibrillation or long-standing persistent atrial fibrillation is associated with success rates of 45-50% at 1 year. To address the challenge of ablating patients with persistent atrial fibrillation, several approaches have been proposed. Atrial scar-based catheter ablation is a promising strategy for ablation of persistent atrial fibrillation.In this review, we outline the role of atrial scar/fibrosis in the pathophysiology of atrial fibrillation and how this encouraged clinical studies assessing the atrial substrate using scar-based mapping. We highlight current approaches to voltage mapping of atrial scar in patients with atrial fibrillation. The characteristics, techniques, and outcomes of recently published studies evaluating scar-based catheter ablation strategies for the treatment of atrial fibrillation are discussed. Finally, we explore the role of noninvasive tools such as delayed enhancement MRI to assess the atrial fibrillation substrate.In summary, the optimal catheter ablation strategy for persistent atrial fibrillation remains unknown. Current data highlight the need for a better understanding of the substrate and mechanisms of arrhythmia maintenance in this population. Atrial scar-based catheter ablation has recently emerged as a promising strategy for ablation of atrial fibrillation. However, the available data have limitations that preclude definitive conclusions regarding the utility of this strategy. Further research is needed to assess the role of scar-based ablation for persistent atrial fibrillation.

Risks associated with exposure to ionizing radiation in patients undergoing electrophysiology procedures and interventional cardiac electrophysiologists performing these procedures are a serious concern. Strategies to reduce radiation exposure are of obvious importance. In addition, interventional cardiac electrophysiologists have to perform procedures wearing heavy lead protection for prolonged periods, making them prone to cervical and lumbar spinal injuries.Recently developed technologies, such as low-exposure radiographic imaging, novel radiographic imaging protection systems, nonfluoroscopic mapping systems using image integration, and remote catheter manipulation systems have been successful in reducing ionizing radiation exposure in the electrophysiology laboratory. The efficacy and safety of these technologies are being evaluated in clinical trials. In addition, economic analyses are being performed to evaluate these novel systems. The use of nonweight-bearing radiation protection devices and ergonomic design of the electrophysiology laboratory aim to reduce the incidence of occupational injuries in interventional cardiac electrophysiologists.There is need for ongoing development and evaluation of new technologies to minimize exposure to ionizing radiation during electrophysiologic procedures. In addition, ergonomic planning of the electrophysiology laboratory and training of interventional cardiac electrophysiologists are crucial to occupational injury prevention.

The purpose of this review is to understand the epidemiology, clinical features, etiopathogenesis, and management of atrioesophageal fistula (AEF) after atrial fibrillation (AF) ablation. The incidence of AEF after AF ablation is 0.015%-0.04%. The principal clinical features include fever, dysphagia, upper gastrointestinal bleeding, sepsis, and embolic strokes. The close proximity of the esophagus to the posterior left atrial wall is responsible for esophageal injury during ablation. Prophylactic proton pump inhibitors, esophageal temperature monitoring, visualization of the esophagus during catheter ablation, esophageal protection devices, and avoidance of energy delivery in close proximity to the esophagus play an important role in preventing esophageal injury. Early surgical repair or esophageal stenting are the mainstay of treatment. Eliminating esophageal injury during AF ablation is of utmost importance in preventing AEF. A high index of suspicion and early intervention is necessary to prevent fatal outcomes.

Introduction Sarcoidosis is a granulomatous disease of unknown etiology, which involves the heart in 5–25% of cases. Although ventricular tachycardia (VT) has been reported as the first presentation of sarcoidosis, its prevalence has not previously been investigated. In this prospective study, we sought to systematically investigate the prevalence of cardiac sarcoidosis (CS) in patients presenting with monomorphic VT (MMVT) and no previous history of sarcoidosis. Methods Consecutive patients presenting with MMVT to a tertiary care center were screened for inclusion. Patients with idiopathic VT, VT secondary to coronary artery disease, or prior diagnosis of sarcoidosis were excluded. Included patients underwent F-18-fluorodeoxyglucose positron emission tomography (PET) scan. In subjects with PET scanning suggestive of active myocardial inflammation, histological diagnosis was confirmed through extracardiac or endomyocardial biopsy (EMB). Results A total of 182 patients presented to our institution with VT between February 2010 and September 2012 and 14 subjects met inclusion criteria. Within this group, six of 14 (42%) patients had abnormal PET scans suggesting active myocardial inflammation. Four of the six patients had tissue biopsies that were diagnostic of sarcoidosis; the remaining two patients had guided EMB indicating nonspecific myocarditis. Atrioventricular block was observed in three of four (75%) patients with CS and none in 10 of the others (P = 0.022). Three of the four patients had pulmonary sarcoidosis and one patient had isolated CS. All four patients were treated with corticosteroids. Conclusion In this prospective study, four of 14 (28%) patients presenting with MMVT (without idiopathic VT, ischemic VT, or known sarcoidosis) had CS as the underlying etiology. Clinicians should consider screening for CS in patients with unexplained MMVT.

Background Patients who receive appropriate implantable cardioverter defibrillator (ICD) shocks have a subsequent adverse prognosis. Most data suggest that patients with inappropriate ICD shocks also have a subsequent adverse prognosis, although this is more controversial. The shocks may be an epiphenomenon, that is, a marker of underlying disease progression; however, it cannot be excluded that shocks cause direct myocardial damage. This latter question is difficult to clarify as the arrhythmia provoking the shock can also cause troponin release. Inappropriate shocks secondary to lead fracture are an ideal situation to examine this question; any troponin release in an otherwise well and hemodynamically stable patient, is likely due directly to the shocks. Methods All patients with Fidelis lead fracture admitted to our institution with inappropriate shocks were included in this study. Troponin (I or T) was considered positive if the level was above the 99th percentile reference cutoff. Results Elevated troponin levels were recorded in 16 of 22 patients (73%). Patients with elevated troponin received a higher number of shocks (20.3 ± 30.1 vs 5.3 ± 4.8, P = 0.07) compared with patients with normal troponin. Very elevated troponin levels (>0.8 mcg/L) were seen in five of 22 (22%) patients. The mean peak troponin level for these five patients was 7.06 ± 8.56 mcg/L; two patients had troponin levels that would be expected from a medium-sized myocardial infarction or severe myocarditis. Conclusion Troponin elevation occurred in the majority of our patients after inappropriate ICD discharges secondary to lead fracture. This indicates that ICD shocks can cause myocardial injury.

Background— The use of cardiac implantable electronic devices (CIED) is increasing, and their associated infections result in significant morbidity and mortality. The introduction of better cardiac imaging techniques could be useful for diagnosing this condition and guiding therapy. Our objective was to systematically assess the diagnostic accuracy of Fluor-18-fluorodeoxyglucose positron emission tomography and computed tomography , labeled leukocyte scintigraphy (LS), and Gallium-67 citrate scintigraphy for the diagnosis of CIED infection. Methods and Results— A systematic review of the literature and meta-analysis on the use of all 3 modalities in CIED infection were conducted. Pooled sensitivity, specificity, and summary receiver operating characteristic curves of each imaging modalities were determined. The literature search identified 2493 articles. A total of 13 articles (11 studies for 18 F-FDG PET-CT and 2 for LS), met the inclusion criteria. No studies for 67 Ga citrate scintigraphy met the inclusion criteria. The pooled sensitivity of 18 F-FDG PET-CT for the diagnosis of CIED infection was 87% (95% CI, 82%–91%) and pooled specificity was 94% (95% CI, 88%–98%). The summary receiver operating characteristic curve analysis demonstrated good overall accuracy, with an area under the curve of 0.935. There were insufficient data to do a meta-analysis for LS, but both studies reported sensitivity above 90% and specificity of 100%. Conclusions— Both 18 F-FDG PET-CT and LS yield high sensitivity, specificity, and accuracy, and thus seem to be useful for the diagnosis of CIED infection, based on robust data for 18 F-FDG PET-CT but limited data for LS. When available, 18 F-FDG PET-CT may be preferred.

Premature ventricular contraction (PVC)-induced cardiomyopathy is increasingly being recognized as a reversible cause of left ventricular (LV) systolic dysfunction (LVSD). The diagnosis of PVC-induced cardiomyopathy is considered in subjects with high PVC burdens (> 10,000 per 24 hours) after excluding other known causes of LVSD. PVC suppression is the mainstay of the management of PVC-induced cardiomyopathy, in addition to proven evidence-based medical therapy recommended for subjects with LVSD. Management strategies for PVC-induced cardiomyopathy include medical therapy and/or catheter ablation, with an increasing role for catheter ablation as a first-line therapy in view of the potential for permanent suppression of PVCs. Recovery of LVSD is typically a gradual process over months after effective suppression of PVCs. Last, asymptomatic patients with high PVC burdens and preserved LV systolic function appear to be at low risk over the intermediate term for developing LVSD. However, it is prudent to monitor LV function periodically because of the potential for deterioration of LV function observed during long-term follow-up in some subjects.

Objectives: We aimed to develop diagnostic criteria for the short QT syndrome (SQTS) to facilitate clinical evaluation of suspected cases.Background: The SQTS is a cardiac channelopathy associated ...

Left ventricular systolic dysfunction (LVSD) is a risk factor for atrial fibrillation (AF), but the atrial cellular electrophysiological mechanisms in humans are unclear.This study sought to investigate whether LVSD in patients who are in sinus rhythm (SR) is associated with atrial cellular electrophysiological changes that could predispose to AF.Right atrial myocytes were obtained from 214 consenting patients in SR who were undergoing cardiac surgery. Action potentials or ion currents were measured using the whole-cell-patch clamp technique.The presence of moderate or severe LVSD was associated with a shortened atrial cellular effective refractory period (ERP) (209 +/- 8 ms; 52 cells, 18 patients vs 233 +/- 7 ms; 134 cells, 49 patients; P0.05); confirmed by multiple linear regression analysis. The left ventricular ejection fraction (LVEF) was markedly lower in patients with moderate or severe LVSD (36% +/- 4%, n = 15) than in those without LVSD (62% +/- 2%, n = 31; P0.05). In cells from patients with LVEFor= 45%, the ERP and action potential duration at 90% repolarization were shorter than in those from patients with LVEF45%, by 24% and 18%, respectively. The LVEF and ERP were positively correlated (r = 0.65, P0.05). The L-type calcium ion current, inward rectifier potassium ion current, and sustained outward ion current were unaffected by LVSD. The transient outward potassium ion current was decreased by 34%, with a positive shift in its activation voltage, and no change in its decay kinetics.LVSD in patients in SR is independently associated with a shortening of the atrial cellular ERP, which may be expected to contribute to a predisposition to AF.

Endothelin-1 (ET-1) is elevated in patients with atrial fibrillation (AF) and heart failure. We investigated effects of ET-1 on human atrial cellular electrophysiological measurements expected to influence the genesis and maintenance of AF. Action potential characteristics and L-type Ca(2+) current (I(CaL)) were recorded by whole cell patch clamp, in atrial isolated myocytes obtained from patients in sinus rhythm. Isoproterenol (ISO) at 0.05 muM prolonged the action potential duration at 50% repolarisation (APD(50): 54 +/- 10 vs. 28 +/- 5 ms; P < 0.05, N = 15 cells, 10 patients), but neither late repolarisation nor cellular effective refractory period (ERP) were affected. ET-1 (10 nM) reversed the effect of ISO on APD(50), and had no basal effect (in the absence of ISO) on repolarisation or ERP. During repetitive stimulation, ISO (0.05 microM) produced arrhythmic depolarisations (P < 0.05). Each was abolished by ET-1 at 10 nM (P < 0.05). ISO (0.05 microM) increased peak I(CaL) from -5.5 +/- 0.4 to -14.6 +/- 0.9 pA/pF (P < 0.05; N = 79 cells, 34 patients). ET-1 (10 nM) reversed this effect by 98 +/- 10% (P < 0.05), with no effect on basal I(CaL). Chronic treatment of patients with a beta-blocker did not significantly alter basal APD(50) or I(CaL), the increase in APD(50) or I(CaL) by 0.05 microM ISO, nor the subsequent reversal of this effect on APD(50) by 10 nM ET-1. The marked anti-adrenergic effects of ET-1 on human atrial cellular action potential plateau, arrhythmic depolarisations and I(CaL), without affecting ERP and independently of beta-blocker treatment, may be expected to contribute a potentially anti-arrhythmic influence in the atria of patients with AF and heart failure.