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Background: Desmoplakin (DSP) variants are associated with left-predominant or biventricular arrhythmogenic cardiomyopathy. Exercise promotes penetrance and sustained ventricular arrhythmias (VA) in right-sided arrhythmogenic right ventricular cardiomyopathy, but its effect is unknown in DSP variant carriers., Objectives: To assess whether exercise is associated with clinical outcomes among individuals with a pathogenic or likely pathogenic (P/LP) DSP variant., Methods: Adults with P/LP DSP variants were interviewed about physical activity from age 10. Endurance athletes were defined based on a mean exercise dose >24 metabolic equivalent hours/week (METhr/wk) of moderate to vigorous intensity exercise. Lifetime survival free from VA (ventricular tachycardia/fibrillation or appropriate ICD therapy), clinical heart failure (HF) (presentation to the emergency department or hospitalization with HF), and myocardial injury events characteristic of DSP-cardiomyopathy (symptoms, elevated troponin, imaging with non-obstructive coronaries) were examined with the Kaplan-Meier method and Cox regression models., Results: Participants (N=100, 66% female, age 36 ± 15 years) were active with a median 28.4 METhr/wk (IQR 14.8-46) of pre-baseline evaluation exercise, and just 8 individuals continued athlete level exercise post-baseline evaluation. In multivariable analyses, endurance athletes (60%) had no worse survival free from VA [HR 1.00 (95% CI 0.5-1.98)] or clinical HF [HR 0.86 (95% CI 0.36-2.05)] but their risk for myocardial injury was elevated [HR 2.37 (95% CI 1.11-5.05)]. Furthermore, myocardial injury episodes were strongly associated with an elevated risk of both VA [HR 7.86 (95% CI 3.56-17.33)] and clinical HF [HR 10.28 (95% CI 2.95-35.83)] thereafter., Conclusions: Endurance exercise may promote progression of DSP-cardiomyopathy by increasing risk of myocardial injury episodes, but the effect on VA and clinical HF is less clear. This study informs shared decision-making exercise and sports participation discussions., (Copyright © 2024. Published by Elsevier Inc.)

Background: In atrial fibrillation (AF) management, understanding left atrial (LA) substrate is crucial. While both electroanatomic mapping (EAM) and late gadolinium enhancement magnetic resonance imaging (LGE-MRI) are accepted methods for assessing the atrial substrate and are associated with ablation outcome, recent findings have highlighted discrepancies between low-voltage areas (LVAs) in EAM and LGE areas., Objective: The purpose of this study was to explore the relationship between LGE regions and unipolar and bipolar LVAs using multipolar high-density mapping., Methods: Twenty patients scheduled for AF ablation underwent preablation LGE-MRI. LA segmentation was conducted using a deep learning approach, which subsequently generated a 3-dimensional mesh integrating the LGE data. High-density EAM was performed in sinus rhythm for each patient. The electroanatomic map and LGE-MRI mesh were coregistered. LVAs were defined using cutoffs of 0.5 mV for bipolar voltage and 2.5 mV for unipolar voltage. The correspondence between LGE areas and LVAs in the LA was analyzed using confusion matrices and performance metrics., Results: A considerable 87.3% of LGE regions overlapped with unipolar LVAs, compared with only 16.2% overlap observed with bipolar LVAs. Across all performance metrics, unipolar LVAs outperformed bipolar LVAs in identifying LGE areas (precision: 78.6% vs 61.1%; sensitivity: 87.3% vs 16.2%; F 1 score: 81.3% vs 26.0%; accuracy: 74.0% vs 35.3%)., Conclusion: Our findings demonstrate that unipolar LVAs strongly correlate with LGE regions. These findings support the integration of unipolar mapping alongside bipolar mapping into clinical practice. This would offer a nuanced approach to diagnose and manage AF by revealing critical insights into the complex architecture of the atrial substrate., Competing Interests: Disclosures The authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The Efficacy of Delayed Enhancement MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation of Atrial Fibrillation randomized trial showed no difference in atrial fibrillation (AF) recurrence with additional delayed enhancement magnetic resonance imaging (DE-MRI) fibrosis-targeted ablation to pulmonary vein isolation (PVI) in persistent AF., Objective: We evaluated the effect of lesion delivery on ablation-induced scarring and AF recurrence., Methods: Lesions delivered, targeting fibrotic and nonfibrotic areas identified from preablation DE-MRI, were studied in relation to ablation-induced scarring on 3-month DE-MRI, including their association with arrhythmia recurrence., Results: A total of 593 patients treated with radiofrequency were analyzed: 293 (49.4%) underwent PVI and 300 (50.6%) underwent additional fibrosis-guided ablation. Lesion analysis showed that 80.9% in the MRI fibrosis-guided group vs 16.5% in the PVI group (P < .001) had ≥40% of baseline fibrosis targeted. MRI assessment of ablation-induced scar showed that 44.8% of fibrosis-guided ablation and 15.5% of PVI had ≥40% of their fibrosis covered by scar (P < .001), demonstrating significant attenuation from lesions delivered to scar formed. In the overall population, fibrosis coverage with scar was not associated with recurrence (hazard ratio [HR] 0.90; 95% confidence interval [CI] 0.80-1.01; P = .08 per 20% increase). In patients with baseline fibrosis < 20%, fibrosis coverage with scar was associated with lower recurrence than PVI (HR 0.85; 95% CI 0.73-0.97; P = .03), whereas the association was not significant when baseline fibrosis ≥ 20% (HR 0.97; 95% CI 0.80-1.17; P = .77). Significant center variation was observed in fibrosis targeting and coverage with scarring., Conclusion: Radiofrequency ablation lesions do not uniformly result in scar formation. A post hoc analysis suggests reduced arrhythmia recurrence when ablation-induced scarring covers fibrotic regions in patients with low baseline fibrosis., Competing Interests: Disclosures Dr Marrouche reported other from Marrek (founder) and from ECG Check (previous shareholder) outside the submitted work and a patent issued for MRI fibrosis imaging. Dr Wazni reported personal fees (for consulting services) from Biosense Webster and Boston Scientific during the conduct of the study. Dr Greene reported personal fees from DURECT Corporation, Janssen Pharmaceuticals, and Pfizer and grants from Boehringer Ingelheim, AstraZeneca, and CSL outside the submitted work. Dr Dean reported grants from Boston Scientific, Medtronic, Siemens, Biosense Webster, and Abbott during the conduct of the study and grants from the National Institutes of Health outside the submitted work. Dr Kholmovski reported personal fees and other (share ownership) from Marrek during the conduct of the study and outside the submitted work, grants from Medtronic outside the submitted work, and a patent issued for US 9713436 licensed to Marrek, US 10004425 licensed to Marrek, and US 10726545 licensed to Marrek. Dr Mansour reported personal fees (for consulting services) from Biosense Webster, Boston Scientific, and Medtronic and personal fees (holding equity) from EPD Solutions and New Pace Ltd outside the submitted work. Dr Marchlinski reported personal fees (scientific advisory board) from Abbott Medical, Biosense Webster, and Medtronic outside the submitted work. Dr Wilber reported other (executive committee for the clinical trial) from Abbott and Boston Scientific; other (coprimary investigator, clinical trial) from AtriCure; grants from Abbott, AtriCure, and Biosense Webster; and personal fees from the American College of Cardiology Foundation (Editor-in-Chief of the Journal of the American College of Cardiology editor’s page), Biosense Webster (consulting), and Medtronic (lectures for fellows) outside the submitted work. Dr Jaïs reported grants from Biosense Webster and Boston Scientific during the conduct of the study and grants from Acutus and Medtronic outside the submitted work. Dr Sanders reported other (advisory board and research grants to his institution) from Medtronic, Abbott Medical, and Boston Scientific; other (advisory board) from CathRx and PaceMate outside the submitted work; and support by a practitioner fellowship from the National Health and Medical Research Council of Australia. Dr Brachmann reported grants from Medtronic and Biotronik during the conduct of the study and personal fees from Medtronic outside the submitted work. Dr Bax reported departmental unrestricted research grants from Abbott, Edwards Lifesciences, Medtronic, Biotronik, Boston Scientific, GE Healthcare, Novartis, and Bayer outside the submitted work. Dr Deneke reported grants (education) from Biotronik and personal fees (speaker) from Abbott and Boston Scientific (scientific committee) outside the submitted work. Dr Calkins reported personal fees from Biosense Webster, Abbott, and Boston Scientific outside the submitted work. No other disclosures were reported., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society., Competing Interests: Data availability No new data were generated or analyzed in support of this research., (Copyright © 2024. Published by Elsevier Inc.)

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetic heart disease associated with life-threatening ventricular arrhythmias. Diagnosis of ARVC is based on the 2010 Task Force Criteria (TFC), application of which often requires clinical expertise at specialized centers., Objective: The purpose of this study was to develop and validate an electrocardiogram (ECG) deep learning (DL) tool for ARVC diagnosis., Methods: ECGs of patients referred for ARVC evaluation were used to develop (n = 551 [80.1%]) and test (n = 137 [19.9%]) an ECG-DL model for prediction of TFC-defined ARVC diagnosis. The ARVC ECG-DL model was externally validated in a cohort of patients with pathogenic or likely pathogenic (P/LP) ARVC gene variants identified through the Geisinger MyCode Community Health Initiative (N = 167)., Results: Of 688 patients evaluated at Johns Hopkins Hospital (JHH) (57.3% male, mean age 40.2 years), 329 (47.8%) were diagnosed with ARVC. Although ARVC diagnosis made by referring cardiologist ECG interpretation was unreliable (c-statistic 0.53; confidence interval [CI] 0.52-0.53), ECG-DL discrimination in the hold-out testing cohort was excellent (0.87; 0.86-0.89) and compared favorably to that of ECG interpretation by an ARVC expert (0.85; 0.84-0.86). In the Geisinger cohort, prevalence of ARVC was lower (n = 17 [10.2%]), but ECG-DL-based identification of ARVC phenotype remained reliable (0.80; 0.77-0.83). Discrimination was further increased when ECG-DL predictions were combined with non-ECG-derived TFC in the JHH testing (c-statistic 0.940; 95% CI 0.933-0.948) and Geisinger validation (0.897; 95% CI 0.883-0.912) cohorts., Conclusion: ECG-DL augments diagnosis of ARVC to the level of an ARVC expert and can differentiate true ARVC diagnosis from phenotype-mimics and at-risk family members/genotype-positive individuals., Competing Interests: Disclosures Dr Calkins is a consultant for Medtronic Inc., Biosense Webster, Pfizer, StrideBio, Abbott, and Tenaya; and receives research support from Boston Scientific. Dr James receives research support from Lexeo Therapeutics and Arvada Therapeutics; and is a past consultant for Pfizer, Lexeo, and StrideBio. All other authors have no conflicts of interest disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Early recurrence of atrial tachyarrhythmias (ERAT) within 3 months of thermal ablation for atrial fibrillation (AF) is common and often considered transient. Pulsed field ablation (PFA) is a nonthermal energy source in which ERAT is not well described., Objective: The purpose of this study was to analyze ERAT in patients with AF undergoing PFA in the Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF (PULSED AF) trial., Methods: This analysis included 154 (52.4%) paroxysmal AF and 140 (47.6%) persistent AF who had ≥10 rhythm assessments during the 90-day blanking period. ERAT was defined as any instance of ≥30 seconds of AF, atrial flutter, or atrial tachycardia on transtelephonic monitoring (weekly and symptomatic) or ≥10 seconds on electrocardiography (at 3 months), both within 90 days. Late recurrence of atrial tachyarrhythmias (LRAT) was defined as observed atrial tachyarrhythmias between 90 days and 12 months., Results: The overall prevalence of ERAT was 27.1% in patients with paroxysmal AF and 31.6% in patients with persistent AF. In patients with ERAT, 73% had ERAT onset within the first month of the procedure. The presence of ERAT was associated with LRAT in patients with paroxysmal AF (hazard ratio 6.4; 95% confidence interval 3.6-11.3) and patients with persistent AF (hazard ratio 3.8; 95% confidence interval 2.2-6.6). Yet, in 29.4% of patients with paroxysmal AF and 34.3% of patients with persistent AF with ERAT, LRAT was not observed. LRAT was positively correlated with the number of ERAT observations., Conclusion: ERAT after PFA predicted LRAT in patients with paroxysmal and persistent AF. However, the concept of a blanking period after PFA is still valid, as approximately one-third of patients with ERAT did not continue to have LRAT during follow-up and may not need reablation., Competing Interests: Disclosures Dr Tarakji, Mr Cerkvenik, and Dr van Bragt are employees and stockholders of Medtronic. Dr Boersma’s cardiology department receives consultation funds from Medtronic, Boston Scientific (BS), Abbott Medical (AM), Adagio Medical, and ZOLL. Dr Natale receives grants and/or consultation funds from Medtronic, Abbott, Biosense Webster (BW), Biotronik, BS, and iRhythm. Dr Haines receives grants and/or consultation funds from Medtronic. Dr DeLurgio receives grants, consultation funds, and/or honoraria funds from Medtronic, AtriCure, and BS. Dr Sood receives consultation or honoraria funds from Johnson & Johnson, Abbott, BS, AtriCure, Bristol Myers Squibb, and Pfizer. Dr Marchlinski receives grants, consultation funds, and/or honoraria funds from Medtronic, BW, AM, and Biotronik. Dr Calkins receives grants, consultation funds, and/or honoraria funds from Medtronic, BS, AM, AtriCure, and BW. Dr Hoyt receives grants and/or consultation funds from Medtronic and AM. Dr Sanders receives grants, consultation funds, and/or honoraria funds from Medtronic, BS, AM, Becton Dickinson, PaceMate, and CathRx. Dr Packer receives grants and/or consultation funds from Medtronic. Dr Mittal receives consultation funds from Medtronic and BS. Dr Di Biase is a consultant for BW, Stereotaxis, and iRhythm and has received speaker honoraria/travel from BW, AM, BS, Medtronic, Biotronik, AtriCure, Siemens, and ZOLL. Dr Tada receives honoraria and/or grants from Medtronic, Daiichi Sankyo, AM, Nippon Boehringer Ingelheim, Eli Lilly, Otsuka Pharmaceutical, Marubun Tsusyo, Biotronik, Bristol Myers Squibb, BS, and Novartis Pharma. Dr Tomita receives research funding from Boehringer Ingelheim, Bayer, Daiichi Sankyo, BS, AM, and Biotronik and speakers’ honorarium from Boehringer Ingelheim, Bayer, Daiichi Sankyo, and Bristol Myers Squibb. Dr Tomita is also a concurrent professor of an endowment department supported by Medtronic Japan, Japan Lifeline, and Fukuda Denshi Kitatohoku Hanbai. Dr Kuck receives grants and/or consultation funds from Medtronic and Cardiovalve. Dr Verma receives grants and/or consultation funds from Medtronic, BW, Bayer, MedLumics, Adagio Medical, and BS. The others have nothing to declare., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) patients at high risk for stroke and for bleeding may be unsuitable for either oral anticoagulation or endocardial left atrial appendage (LAA) occlusion. However, minimally invasive, epicardial left atrial appendage exclusion (LAAE) may be an option., Objective: The purpose of this study was to evaluate outcomes of LAAE in high-risk AF patients not receiving oral anticoagulation., Methods: A retrospective analysis of Medicare claims data was conducted to evaluate thromboembolic events in AF patients who underwent LAAE compared to a 1:4 propensity score-matched group of patients who did not receive LAAE (control). Neither group was receiving any oral anticoagulation at baseline or follow-up. Fine-Gray models estimated hazard ratios and evaluated between-group differences. Bootstrapping was applied to generate 95% confidence intervals (CIs)., Results: The LAAE group (n = 243) was 61% male (mean age 75 years). AF was nonparoxysmal in 70% (mean CHA 2 DS 2 -VASc score 5.4; mean HAS-BLED score 4.2). The matched control group (n = 972) had statistically similar characteristics. One-year adjusted estimates of thromboembolic events were 7.3% (95% CI 4.3%-11.1%) in the LAAE group and 12.1% (95% CI 9.5%-14.8%) in the control group. Absolute risk reduction was 4.8% (95% CI 0.6%-8.9%; P = .028). Adjusted hazard ratio for thromboembolic events for LAAE vs non-LAAE was 0.672 (95% CI 0.394-1.146)., Conclusion: In AF patients not taking oral anticoagulation who are at high risk for stroke and for bleeding, minimally invasive, thoracoscopic, epicardial LAAE was associated with a lower rate of thromboembolic events., Competing Interests: Disclosures Dr Rose reports receiving honoraria from AtriCure, Boston Scientific, Cheisi-USA, CSL-Behring, Medtronic, and Viz. Dr DiGiorgi reports receiving consulting fees from AtriCure. Dr Ramlawi reports being a consultant and advisory board member of AtriCure, Boston Scientific, Corcym, Medtronic, and Shockwave Medical. Dr Pulungan and Dr Teigland are employees of Inovalon. Dr Calkins reports receiving lecture honoraria from Abbott, AtriCure, and Boston Scientific., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The appropriate use criteria (AUCs) are a diverse group of indications aimed to better evaluate the benefits of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy., Objective: The purpose of this study was to quantify the proportion of ICD and cardiac resynchronization therapy with defibrillator (CRT-D) implants as appropriate, may be appropriate (MA), or rarely appropriate (RA) on the basis of the AUC guidelines., Methods: This is a multicenter retrospective study of patients within the National Cardiovascular Data Registry undergoing ICD implantation between April 2018 and March 2019 at >1500 US hospitals. The appropriateness of ICD implants was adjudicated using the AUC., Results: Of 309,318 ICDs, 241,438 were primary prevention implants (78.1%) and 67,880 secondary prevention implants (21.9%); 243,532 (79%) were mappable to the AUC. For primary prevention, 185,431 ICDs (96.4%) were appropriate, 5660 (2.9%) MA, and 1205 (0.6%) RA. For secondary prevention, 47,498 ICDs (92.7%) were appropriate, 2581 (5%) MA, and 1157 (2.3%) RA. A significant number of RA devices were implanted in patients with New York Heart Association class IV heart failure who were ineligible for advanced therapies (53.9%) and those with myocardial infarction within 40 days (18.1%). The appropriateness of the pacing lead was more variable, with 48,470 dual-chamber ICD implants (62%) being classified as appropriate, 29,209 (37.4%) MA, and 448 (0.6%) RA. Among CRT-D implants, 63,848 (82.2%) were appropriate, 9900 (12.7%) MA, and 3940 (5.1%) RA for left ventricular pacing. A total of 99,754 implants were deemed appropriate but excluded from Centers for Medicare & Medicaid Services National Coverage Determination. More than 92% of hospitals had an RA implant rate of <4%., Conclusion: In this large national registry, 95% of mappable ICD and CRT-D implants were considered appropriate, with <2% of RA implants. Nearly 100,000 appropriate implants are excluded by Centers for Medicare & Medicaid Services National Coverage Determination., Competing Interests: Disclosures Dr Yousuf serves as a consultant for Medtronic, Boston Scientific, and Zoll and is a member of the American College of Cardiology NCDR Reporting and Methodologies Committee, Electrophysiology NCDR Registry Suite Steering Committee, Heart Rhythm Society's Digital Health Committee. Dr Atwater serves as a consultant for Medtronic, Abbott, Biotronik, Biosense Webster, and Bristol Myers Squibb. Dr Steinberg has received research support from National Insitutes of Health (#K23HL143156), American Heart Association/Patient-Centered Outcomes Research Institute (PCORI), Boston Scientific, Sanofi, and AltaThera and is consulting to Sanofi, InCarda, Milestone, Pfizer, and AltaThera. He also serves as Chair of the Steering Committee for the NCDR EP registries. Dr Calkins serves as a consultant for Biosense Webster, Medtronic, Abbott Medical, and AtriCure. The rest of the authors report no conflicts of interest., (Copyright © 2024. Published by Elsevier Inc.)

Background: The diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) is challenging because of nonspecific clinical findings and lack of conclusive answers from genetic testing (ie, an ARVC-related variant is neither necessary nor sufficient for diagnosis). Despite the revised 2010 Task Force Criteria, patients are still misdiagnosed with ARVC., Objective: In patients referred for ARVC, we sought to identify the clinical characteristics and diagnostic confounders for those patients in whom ARVC was ultimately ruled out., Methods: Patients who were referred to our center with previously diagnosed or suspected ARVC (between January 2011 and September 2019; N = 726) were included in this analysis., Results: Among 726 patients, ARVC was ruled out in 365 (50.3%). The most common presenting symptoms in ruled-out patients were palpitations (n = 139, 38.1%), ventricular arrhythmias (n = 62, 17.0%), and chest pain (n = 53, 14.5%). On the basis of outside evaluation, 23.8% of these patients had received implantable cardioverter-defibrillators (ICDs) and device extraction was recommended in 9.0% after reevaluation. An additional 5.5% had received ICD recommendations, all of which were reversed on reevaluation. The most frequent final diagnoses were idiopathic premature ventricular contractions/ventricular tachycardia/ventricular fibrillation (46.6%), absence of disease (19.2%), and noncardiac presyncope/syncope (17.5%). The most common contributor to diagnostic error was cardiac magnetic resonance imaging, including mistaken right ventricular wall motion abnormalities (33.2%) and nonspecific fat (12.1%)., Conclusion: False suspicion or misdiagnosis was found in the majority of patients referred for ARVC, resulting in inappropriate ICD implantation or recommendation in 14.5% of these patients. Misdiagnosis or false suspicion was most commonly due to misinterpretation of cardiac magnetic resonance imaging., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Freedom from atrial arrhythmia (AA) recurrence ≥30 seconds after pulsed field ablation (PFA) in patients with atrial fibrillation (AF) was reported in PULSED AF (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF; ClinialTrials.gov Identifier: NCT04198701). AA burden may be a more clinically meaningful endpoint., Objective: The purpose of this study was to determine the influence of monitoring strategies on AA detection and AA burden association with quality of life (QoL) and health care utilization (HCU) after PFA., Methods: Patients underwent 24-hour Holter monitoring at 6 and 12 months and weekly, and symptomatic transtelephonic monitoring (TTM). AA burden post-blanking was calculated as the greater of (1) percentage of AA on total Holter time; or (2) percentage of weeks with ≥1 TTM with AA out of all weeks with ≥1 TTM., Results: Freedom from all AAs varied by >20% when differing monitoring strategies were used. PFA resulted in zero burden in 69.4% of paroxysmal atrial fibrillation (PAF) and 62.2% of persistent atrial fibrillation (PsAF) patients. Median burden was low (<9%). Most PAF and PsAF patients had ≤1 week of AA detection on TTM (82.6% and 75.4%) and <30 minutes of AA per day of Holter monitoring (96.5% and 89.6%), respectively. Only PAF patients with <10% AA burden averaged a clinically meaningful (>19 point) QoL improvement. PsAF patients experienced clinically meaningful QoL improvements irrespective of burden. Repeat ablations and cardioversions significantly increased with higher AA burden (P <.01)., Conclusion: The ≥30-second AA endpoint is dependent on the monitoring protocol used. PFA resulted in low AA burden for most patients, which was associated with clinically relevant improvement in QoL and reduced AA-related HCU., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Early recurrence of atrial tachyarrhythmia (ERAT) is common after pulmonary vein isolation (PVI) and has been associated with an increased risk of late atrial fibrillation (AF) recurrence., Objective: The purpose of this study was to determine the incidence and outcomes of patients experiencing ERAT after PVI using advanced-generation ablation technologies., Methods: This is a prespecified substudy of the CIRCA-DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double-Short vs Standard Exposure Duration) trial, a prospective, randomized, multicenter study comparing PVI with contact force-guided radiofrequency ablation to secondary-generation cryoballoon ablation for paroxysmal AF. All study patients received an implantable cardiac monitor to allow continuous rhythm monitoring. ERAT was defined as any recurrent atrial tachyarrhythmia within the first 90 days after AF ablation., Results: ERAT occurred in 61% of the 346 patients at a median of 12 days (range 1-90 days) after ablation. ERAF was a significant predictor of late recurrence (60.1% with ER vs 25.9% without ER; P <.001) and symptomatic atrial tachyarrhythmia (31.6% with ERAF vs 6.7% without ERAF; P <.001). Receiver operating curve analyses revealed a strong correlation between ERAT timing and burden and late recurrence. Multivariate analysis identified ER timing (hazard ratio [HR] 2.90; 95% confidence interval [CI] 1.41-5.95; P = .004) and burden (HR 1.05 per 1% ER burden; 95% CI 1.04-1.07; P <.001) as strong independent predictors of late recurrence. Incidence rate, timing, burden, and prognostic significance of ER did not differ between the study groups., Conclusion: ERAT remains common after PVI despite use of advanced-generation ablation technologies. Early AF recurrence beyond 3 weeks after ablation is associated with increased risk of late recurrence., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Previous studies of radiofrequency catheter ablation (RFA) of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), relying on limited numbers of procedures, have not reported VT-free survival in parallel for single and multiple procedures (ie, after the last procedure). Data regarding the impact of RFA on VT burden are scarce., Objective: The purpose of this study was to provide new insights on clinical outcomes based on a large series of VT ablation procedures from the current era in ARVC patients., Methods: We evaluated consecutive patients with definite ARVC who underwent RFA procedures between 2009 and 2019 at our center. We assessed VT-free survival, for single and multiple procedures, and changes in VT burden and antiarrhythmic drugs (AADs) after RFA., Results: Among 116 patients, there were 166 RFA procedures, 106 (63.9%) of which involved epicardial ablation. Cumulative freedom from VT after a single procedure was 68.6% and 49.8% at 1 and 5 years, respectively. Cumulative VT-free survival after multiple procedures was 81.8% and 69.6% at 1 and 5 years, respectively. VT burden per RFA was reduced after vs before ablation (mean 0.7 vs 10.0 events/year; P <.001). Furthermore, VT burden per patient was reduced after last ablation vs before first ablation (mean 0.5 vs 10.9 events/year; P <.001). Use of AADs decreased after ablation (22.2% vs 51.9%; P <.001)., Conclusion: In ARVC patients, RFA provided good VT-free survival after a single procedure, with multiple procedures required for more sustained freedom from VT recurrence. Marked reduction in VT burden permitted discontinuation of AADs., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Recurrent arrhythmia following catheter ablation of atrial fibrillation (AF) may present early, during a standard 3-month blanking period. Early recurrence has been correlated to late recurrence, but the degree to which its absence predicts longer-term success has not been quantified., Objective: The purpose of this study was to explore and quantify the relationship between early and late arrhythmia recurrence, specifically the negative predictive value, that is, the degree to which absence of blanking period recurrence predicts absence of late recurrence., Methods: A systematic literature review and meta-analysis were conducted using statistical methods of a diagnostic test accuracy review. Studies of AF ablation using point-by-point radiofrequency, with repeated monitoring of arrhythmia recurrence including asymptomatic recurrence, and with separate data by AF type, were eligible., Results: Nine studies met the prespecified eligibility criteria. For paroxysmal AF, 89% (confidence interval [CI] 82%-94%) of patients free from early recurrence remained free from late recurrence. The estimate for persistent AF was similar (91%; CI 75%-97%). This finding was robust in sensitivity analyses. Patients with early recurrence had a wider range of likely outcomes with longer-term follow-up., Conclusion: Freedom from AF recurrence during the blanking period is highly predictive of longer-term success in catheter ablation. Clinical trials in this area may be able to leverage these findings to more quickly assess the potential utility of new ablation technologies and methods, for example, by using early surrogate measures of success., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation to treat patients with symptomatic drug-refractory atrial fibrillation (AF)., Objective: The purpose of this study was to assess the safety and efficacy of PVI using the cryoballoon catheter to treat patients with persistent AF., Methods: STOP Persistent AF (ClinicalTrials.gov Identifier: NCT03012841) was a prospective, multicenter, single-arm, Food and Drug Administration-regulated trial designed to evaluate the safety and efficacy of PVI-only cryoballoon ablation for drug-refractory persistent AF (continuous episodes <6 months). The primary efficacy endpoint was 12-month freedom from ≥30 seconds of AF, atrial flutter (AFL), or atrial tachycardia (AT) after a 90-day blanking period. The prespecified performance goals were set at >40% and <13% for the primary efficacy and safety endpoints, respectively. Secondary endpoints assessed quality of life using the AFEQT (Atrial Fibrillation Effect on Quality of Life) and SF (Short Form)-12 questionnaires., Results: Of 186 total enrollments, 165 subjects (70% male; age 65 ± 9 years; left atrial diameter 4.2 ± 0.6 cm; body mass index 31 ± 6) were treated at 25 sites in the United States, Canada, and Japan. Total procedural, left atrial dwell, and fluoroscopy times were 121 ± 46 minutes, 102 ± 41 minutes, and 19 ± 16 minutes, respectively. At 12 months, the primary efficacy endpoint was 54.8% (95% confidence [CI] 46.7%-62.1%) freedom from AF, AFL, or AT. There was 1 primary safety event, translating to a rate of 0.6% (95% CI 0.1%-4.4%). AFEQT and SF-12 assessments demonstrated significant improvements from baseline to 12 months postablation (P <.001)., Conclusion: The STOP Persistent AF trial demonstrated cryoballoon ablation to be safe and effective in treating patients with drug-refractory persistent AF characterized by continuous AF episodes <6 months., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Ventricular arrhythmias (VAs) in cardiac sarcoidosis (CS) are frequently refractory to both antiarrhythmic drug (AAD) therapy and catheter ablation (CA). Cardiac sympathetic denervation (CSD) has been shown to reduce VA burden and implantable cardioverter-defibrillator (ICD) shocks in patients with nonischemic cardiomyopathy., Objective: We aimed to report our center's preliminary experience with CSD in patients with known or presumed CS and refractory VAs., Methods: Patients with CS and refractory VAs who underwent CSD at our institution were included. Patient characteristics, procedural outcomes, and number of arrhythmic events including ICD shocks pre- and post-CSD are reported., Results: Five patients with CS (mean age 53 ± 11 years; 2 men [40%]; mean left ventricular ejection fraction 38% ± 11%) underwent CSD for VA refractory to AAD therapy and CA. Four of 5 patients underwent bilateral CSD; 1 patient underwent right-sided sympathectomy only because of poor intraoperative visualization on the left. Procedural complications included hemothorax in 1 patient and azygous vein injury in 1 patient. The median number of ICD shocks in the 6 months pre-CSD was 5. During a median follow-up of 26 months (range 5-29 months), the median number of ICD shocks post-CSD was 0; 1 patient had sustained VA that was below the threshold for device therapy, and 1 patient had symptomatic premature ventricular contractions; both underwent repeat CA. In addition, 1 patient required cardiac transplantation for progressive heart failure., Conclusion: CSD may be a feasible therapeutic adjunct for patients with CS and VA refractory to AAD therapy and CA., (Copyright © 2019. Published by Elsevier Inc.)

Background: The sympathetic nervous system plays an important role in arrhythmogenesis in arrhythmogenic right ventricular cardiomyopathy (ARVC). Sudden cardiac death commonly occurs during exertion, and β-blockers are associated with a reduction in arrhythmia burden. Bilateral cardiac sympathetic denervation (BCSD) has been shown to reduce implantable cardioverter-defibrillator (ICD) shocks in patients with structural heart disease and refractory ventricular tachycardia (VT); however, data in ARVC are sparse., Objective: The purpose of this study was to evaluate the role of BCSD in patients with ARVC and refractory VT., Methods: Consecutive patients with ARVC who underwent BCSD because of refractory VT were included. Number of ICD shocks, sustained VT episodes, VT storm, and antiarrhythmic therapy were assessed and compared before and after the intervention. VT-free survival rate, death, and heart transplantation were also evaluated., Results: Eight patients with ARVC (mean age 32 ± 20 years; 3 men [38%]) underwent sympathectomy for recurrent VT. All patients failed catheter ablation, and 50% had a desmosomal mutation identified. Procedural complications included neuropathic pain, paravertebral venous plexus injury, and pneumothorax. Over a mean follow-up of 1.9 ± 0.9 years, 5 patients (63%) had no VT recurrence. BCSD significantly reduced the number of ICD shocks or sustained VT compared with 1-year pre-BCSD (mean 12.6 ± 18.2 and median 6.5 [interquartile range 4.5-10.5] pre-BCSD vs 0.9 ± 1.4 and 0 [interquartile range 0-1.5] post-BCSD; P = .011). Most of the patients (88%) were on β-blocker therapy alone at the end of follow-up. One patient underwent heart transplantation because of heart failure, and no deaths occurred., Conclusion: BCSD may be an effective option for patients with ARVC and refractory ventricular arrhythmia who have failed conventional treatment modalities., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) affects an estimated 33 million people worldwide, leading to increased mortality and an increased risk of heart failure and stroke. Many AF patient registries exist, but the ability to link and compare data across registries is hindered by differences in the outcome measures collected by each registry and a lack of harmonization., Objectives: The purpose of this project was to develop a minimum set of standardized outcome measures that could be collected in AF patient registries and clinical practice., Methods: AF patient registries were identified through multiple sources and invited to join the workgroup and submit outcome measures. Additional measures were identified through literature searches and reviews of consensus statements. Outcome measures were categorized using the Agency for Healthcare Research and Quality's supported Outcome Measures Framework (OMF). A minimum set of broadly relevant measures was identified. Measure definitions were harmonized through in-person and virtual meetings., Results: One hundred twelve outcome measures, including those from thirteen registries, were curated according to the OMF and then harmonized into a minimum set of measures in the OMF categories of survival (3 measures), clinical response (3 measures), events of interest (9 measures), patient-reported outcomes (2 measures), and resource utilization (3 measures). The harmonized definitions build on existing consensus statements., Conclusions: The harmonized measures represent a minimum set of outcomes that are relevant in AF research and clinical practice. Routine and consistent collection of these measures in registries and in other systems would support creation of a research infrastructure to efficiently address new questions and improve patient outcomes., (Copyright © 2018 Heart Rhythm Society. All rights reserved.)

Background: Contrast-enhanced cardiac computed tomography (CE-CT) provides useful substrate characterization in patients with ventricular tachycardia (VT)., Objective: The purpose of this study was to describe the association between endocardial electrogram measurements and myocardial characteristics on CE-CT, in particular the field of view of electrogram features., Methods: Fifteen patients with postinfarct VT who underwent catheter ablation with preprocedural CE-CT were included. Electroanatomic maps were registered to CE-CT, and myocardial attenuation surrounding each endocardial point was measured at a radius of 5, 10, and 15 mm. The association between endocardial voltage and attenuation was assessed using a multilevel random effects linear regression model, clustered by patient, with best model fit defined by highest log likelihood., Results: A total of 4698 points were included. There was a significant association of bipolar and unipolar voltage with myocardial attenuation at all radii. For unipolar voltage, the best model fit was at an analysis radius of 15 mm regardless of the mapping catheter used. For bipolar voltage, the best model fit was at an analysis radius of 15 mm for points acquired with a conventional ablation catheter. In contrast, the best model fit for points acquired with a multipolar mapping catheter was at an analysis radius of 5 mm., Conclusion: Myocardial attenuation on CE-CT indicates a smaller myocardial field of view of bipolar electrograms using multipolar catheters with smaller electrodes in comparison to standard ablation catheters despite similar interelectrode spacing. Smaller electrodes may provide improved spatial resolution for the definition of myocardial substrate for VT ablation., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Ablation-induced left atrial (LA) edema may result in procedural failure due to reversible pulmonary vein isolation. Conventional T2-weighted magnetic resonance edema imaging is limited by low spatial resolution., Objective: The purpose of this pilot study was to optimize and validate a 3-dimensional (3D) sampling perfection with application-optimized contrasts using different flip-angle evolution (SPACE) sequence for quantification of T2 signal in the LA, and to apply it in recently ablated patients, comparing myocardial edema on T2-SPACE to tissue damage on late gadolinium enhancement (LGE) imaging., Methods: Phantom studies were performed to identify 3D-SPACE parameters for optimal contrast between normal and edematous myocardium. Fourteen AF patients were imaged with both 3D-SPACE and dark-blood turbo-spin echo (DB-TSE) to compare image quality and signal intensity between the 2 techniques. Eight patients underwent pre- and postablation 3D-SPACE and 3D-LGE imaging. Ablation points were co-registered with corresponding myocardial sectors, and ablation-induced changes in T2 and LGE signal intensities were measured., Results: Signal-to-noise ratio and contrast-to-noise ratio were higher on SPACE vs DB-TSE (65.5 ± 33.9 vs 35.7 ± 17.9; P = .01; and 59.4 ± 33.0 vs 32.9 ± 17.7; P = .04, respectively). T2-signal correlated well on 3D-SPACE and DB-TSE, such that each unit increase in TSE intensity correlated with a 0.69-unit increase in SPACE intensity (95% confidence interval 0.56-0.82; P <.001). T2 and LGE signal intensities were acutely increased at ablation sites. The extent of postablation edema was higher compared to LGE, although the spatial distribution of hyperenhancement around pulmonary veins seemed similar in both modalities., Conclusion: T2-SPACE can be used to map the extent of acute postablation edema in the thin LA myocardium, with improved resolution and lower artifact compared to traditional DB-TSE., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

While many studies evaluate predictors of ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC), a systematic review consolidating this evidence is currently lacking. Therefore, we searched MEDLINE and Embase for studies analyzing predictors of ventricular arrhythmias (sustained ventricular tachycardia/fibrillation (VT/VF), appropriate implantable cardioverter-defibrillator therapy, or sudden cardiac death) in patients with definite ARVC, patients with borderline ARVC, and ARVC-associated mutation carriers. In the case of multiple publications on the same cohort, the study with the largest population was included. This yielded 45 studies with a median cohort size of 70 patients (interquartile range 60 patients) and a median follow-up of 5.0 years (interquartile range 3.3 - 6.7 years). The average proportion of arrhythmic events observed was 10.6%/y in patients with definite ARVC, 10.0%/y in patients with borderline ARVC, and 3.7%/y with mutation carriers. Predictors of ventricular arrhythmias were population dependent: consistently predictive risk factors in patients with definite ARVC were male sex, syncope, T-wave inversion in lead >V 3 , right ventricular dysfunction, and prior (non)sustained VT/VF; in patients with borderline ARVC, 2 additional predictors-inducibility during electrophysiology study and strenuous exercise-were identified; and with mutation carriers, all aforementioned predictors as well as ventricular ectopy, multiple ARVC-related pathogenic mutations, left ventricular dysfunction, and palpitations/presyncope determined arrhythmic risk. Most evidence originated from small observational cohort studies, with a moderate quality of evidence. In conclusion, the average risk of ventricular arrhythmia ranged from 3.7 to 10.6%/y depending on the population with ARVC. Male sex, syncope, T-wave inversion in lead >V 3 , right ventricular dysfunction, and prior (non)sustained VT/VF consistently predict ventricular arrhythmias in all populations with ARVC., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Catheter ablation is recommended as a first- or second-line rhythm control therapy for selected patients with atrial fibrillation (AF). There is a wide variability in the periprocedural management of oral anticoagulation in patients undergoing AF ablation., Objective: We aimed to perform an updated meta-analysis of novel oral anticoagulants (NOACs) vs vitamin K antagonists (VKAs) as uninterrupted anticoagulation in patients undergoing AF ablation., Methods: Databases and conference abstracts were searched. Studies were excluded if oral anticoagulants were held at any periprocedural period. The primary outcomes were stroke or transient ischemic attack (TIA) and major bleeding., Results: Twelve studies and 4962 patients were included. Stroke or TIA was rare (NOAC, 0.08%; VKA, 0.16%) and not different between groups (odds ratio [OR] 0.66; 95% confidence interval [CI] 0.19-2.30). The incidence of silent cerebral embolic events was also not significantly different between NOACs (8%) and VKAs (9.6%) (OR 0.86; 95% CI 0.42-1.76). Major bleeding was significantly reduced in the NOAC group (0.9%) as compared with VKA-treated patients (2%) (OR 0.50; 95% CI 0.30-0.84; P < .01). This finding was confirmed in a subgroup analysis of randomized and cohort studies with matched controls (OR 0.45; 95% CI 0.24-0.83; P = .01). There was no significant difference in the outcomes of individual NOACs and VKAs, although these analyses may have been underpowered to detect minor differences in such rare outcomes., Conclusion: In patients undergoing AF ablation, uninterrupted periprocedural NOACs are associated with a low incidence of stroke or TIA and a significant reduction in major bleeding as compared with uninterrupted VKAs., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The clinical profile of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) patients with late presentation is unknown., Objective: The purpose of this study was to characterize the genotype, cardiac phenotype, and long-term outcomes of ARVC/D patients with late presentation (age ≥50 years at diagnosis)., Methods: Five hundred two patients with an ARVC/D diagnosis from Johns Hopkins and Utrecht Registries were studied and long-term clinical outcomes ascertained., Results: Late presentation was seen in 104 patients (21%; 38% PKP2 carriers); 3% were ≥65 years at diagnosis. Sustained ventricular tachycardia was the major (43%) mode of presentation in patients with late presentation, whereas cardiac syncope was infrequent (P <.001). Those with late presentation were significantly less likely to harbor a known pathogenic mutation (53%; P = .005), have less precordial T-wave repolarization changes (P <.001), and have lower ventricular ectopy burden (P = .026). Over median 6-year follow-up, 68 patients with late presentation (65%) experienced sustained ventricular arrhythmias, with similar arrhythmia-free survival at 5-year follow up (P = .48). Left ventricular dysfunction and heart failure were seen in 24 (32%) and 15 patients (14%), respectively, without need for cardiac transplantation. In the late presentation cohort, male sex, pathogenic mutation, right ventricular structural disease, lack of family history, and electrophysiologic study inducibility were associated with increased arrhythmic risk., Conclusion: One-fifth of all ARVC/D patients present after age 50 years, often with sustained ventricular tachycardia, and are less likely to have prior syncope, ECG changes, ventricular ectopy, or identifiable pathogenic mutation. In ARVC/D, late presentation does not confer a benign prognosis and is associated with high arrhythmic risk., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Atrial fibrillation (AF) is an age-related arrhythmia of enormous socioeconomic significance. In recent years, our understanding of the basic mechanisms that initiate and perpetuate AF has evolved rapidly, catheter ablation of AF has progressed from concept to reality, and recent studies suggest lifestyle modification may help prevent AF recurrence. Emerging developments in genetics, imaging, and informatics also present new opportunities for personalized care. However, considerable challenges remain. These include a paucity of studies examining AF prevention, modest efficacy of existing antiarrhythmic therapies, diverse ablation technologies and practice, and limited evidence to guide management of high-risk patients with multiple comorbidities. Studies examining the long-term effects of AF catheter ablation on morbidity and mortality outcomes are not yet completed. In many ways, further progress in the field is heavily contingent on the feasibility, capacity, and efficiency of clinical trials to incorporate the rapidly evolving knowledge base and to provide substantive evidence for novel AF therapeutic strategies. This review outlines the current state of AF prevention and treatment trials, including the foreseeable challenges, as discussed by a unique forum of clinical trialists, scientists, and regulatory representatives in a session endorsed by the Heart Rhythm Society at the 12th Global CardioVascular Clinical Trialists Forum in Washington, DC, December 3-5, 2015., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Epicardial adipose tissue (EAdT) is metabolically active and likely contributes to atrial fibrillation (AF) through the release of inflammatory cytokines into the myocardium or through its rich innervation with ganglionated plexi at the pulmonary vein ostia. The electrophysiologic mechanisms underlying the association between EAdT and AF remain unclear., Objective: The purpose of this study was to investigate the association of EAdT with adjacent myocardial substrate., Methods: Thirty consecutive patients who underwent cardiac computed tomography as well as electroanatomic mapping in sinus rhythm before an initial AF ablation procedure were studied. Semiautomatic segmentation of atrial EAdT was performed and registered anatomically to the voltage map., Results: In multivariable regression analysis clustered by patient, age (-0.01 per year) and EAdT (-0.29) were associated with log bipolar voltage as well as low-voltage zones (<0.5 mV). Age (odds ratio [OR]: 1.02 per year), male gender (OR: 3.50), diabetes (OR: 2.91), hypertension (OR: 2.55), and EAdT (OR: 8.56) were associated with fractionated electrograms, and age (OR: 2.80), male gender (OR: 3.00), and EAdT (OR: 7.03) were associated with widened signals. Age (OR: 1.03 per year) and body mass index (OR: 1.06 per kg/m 2 ) were associated with atrial fat., Conclusion: The presence of overlaying EAdT was associated with lower bipolar voltage and electrogram fractionation as electrophysiologic substrates for AF. EAdT was not a statistical mediator of the association between clinical variables and AF substrate. Body mass index was directly associated with the presence of EAdT in patients with AF., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The feasibility and safety of postmortem cardiovascular implantable electronic device (CIED; pacemaker or defibrillator) retrieval for reuse has been shown. To date, studies indicate a low yield of reusable postmortem CIEDs (17%-30%)., Objective: The purpose of this study was to test the hypothesis that a higher rate of reusable CIEDs would be identified upon postmortem retrieval when an institutional protocol for systematic and routine acquisition, interrogation, reprogramming, and manufacturer analysis was used., Methods: Over a 6-year period, all subjects referred for autopsy underwent concomitant CIED pulse generator retrieval and enrollment in the Johns Hopkins Post-Mortem CIED Registry. CIEDs were interrogated, reprogrammed, and submitted for manufacturer analysis., Results: In total, 84 autopsies had CIEDs (37 pacemakers, 47 implantable cardioverter-defibrillators). CIEDs were implanted 2.84 ± 2.32 years before death, with 30% implanted <1 year before death. Overall, CIED postmortem longevity was 4.79 ± 3.41 years, with 56% demonstrating longevity ≥4 years (this group had an estimated mean longevity of 7.37 ± 2.44 years). Manufacturer analyses uncovered 2 falsely triggered elective replacement indication alerts, confirmed 5 correctly triggered elective replacement indication alerts, identified a recalled pacemaker, and verified that a defibrillator had undergone nonprogrammable hard reset., Conclusion: When a protocol for systematic and routine postmortem CIED retrieval, interrogation, reprogramming, and analysis was used, we noted that >60% of pacemakers and >50% of defibrillators demonstrated normal functional status with projected longevities >7 years on average. Formation of a national hospital-based "CIED donor network" would facilitate larger scale charitable efforts in underserved countries., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Left atrial flutter (LAFL) occurs in patients after atrial fibrillation ablation. Identification of optimal ablation targets to terminate LAFL remains challenging., Objective: The purpose of this study was to use patient-specific models to simulate LAFL and predict optimal ablation targets using a novel approach based on flow network theory., Methods: Late gadolinium-enhanced cardiac magnetic resonance scans from 10 patients with LAFL were used to construct atrial models incorporating fibrosis by investigators blinded to procedural findings. Rapid pacing was applied in silico to induce LAFL. In each LAFL, we represented reentrant wave propagation as an electric flow network and identified the "minimum cut" (MC), which was the smallest amount of tissue that separated the flow into 2 discontinuous components. In silico ablation was applied at MCs, and targets were compared to those that terminated LAFL during catheter ablation., Results: Patient-specific atrial models were successfully generated from patient scans. LAFL was induced in 7 of 10 models. Ablation of MCs terminated LAFL in 4 models and produced new, slower LAFL morphologies in the other 3. For the latter cases, flow analysis was repeated to identify MCs of emergent LAFLs. Ablation of these MCs terminated emergent LAFLs. The MC-based ablation lesions in simulations were similar in length and location to ablation targets that terminated LAFL during catheter ablation for these 7 patients., Conclusion: Personalized atrial simulations can predict ablation targets for LAFL. These simulations provide a powerful tool for planning ablation procedures and may reduce procedural times and complications., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Catheter ablation of ventricular tachycardia (VT) has evolved in recent years, especially in patients with ischemic heart disease. Data from prospective studies show that VT catheter ablation reduces the risk of recurrent VT; however, there is a paucity of data on the effect of VT catheter ablation on mortality and patient-centered outcomes such as quality of life. Performing randomized clinical trials of VT catheter ablation can be fraught with challenges, and, as a result, several prior trials of VT catheter ablation had to be stopped prematurely. The main challenges are inability to blind the patient to therapy to obtain a traditional control group, high crossover rates between the 2 arms of the study, patient refusal to participate in trials in which they have an equal chance of receiving a "pill" vs an invasive procedure, heterogeneity of mapping and ablation techniques as well as catheters and equipment, rapid evolution of technology that may make findings of any long trial less relevant to clinical practice, lack of consensus on what constitutes acute procedural and long-term success, and presentation of patients to electrophysiologists late in the course of their disease. In this article, a panel of experts on VT catheter ablation and/or clinical trials of VT catheter ablation review challenges faced in conducting prior trials of VT catheter ablation and offer potential solutions for those challenges. It is hoped that the proposed solutions will enhance the feasibility of randomized clinical trials of VT catheter ablation., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Prognostic significance of left atrial (LA) function in patients with atrial fibrillation (AF) is poorly defined., Objective: To examine the association of LA function measured with cardiac magnetic resonance (CMR) feature-tracking and AF recurrence following catheter ablation., Methods: One hundred and twenty-one AF patients (72% paroxysmal, mean age 59 ± 10 years) were enrolled. Baseline LA function was measured by calculating passive, active, and total emptying fractions (LAEF) and analysis of global longitudinal strain and strain rates. Patients were followed up for recurrence of AF or atrial tachycardia (AT). Hazard ratios for recurrence were calculated using Cox proportional models adjusted for potential clinical confounders, type of AF, left ventricular ejection fraction, AF duration, LA volume, and late gadolinium enhancement (LGE)., Results: During a mean follow-up of 18 ± 9 months, 52 patients (43%) experienced recurrent AF/AT. Patients with recurrent AF/AT had higher baseline LA volume index and lower LA passive, and total LAEF (P < .05 for all). The baseline peak LA strain and strain rates in all phases of LA function were lower in the AF/AT recurrence group (P < .01 for all). In multivariable analysis total LAEF, peak LA strain, and systolic and late diastolic strain rates were associated with recurrence. Both peak LA strain and total LAEF improved prediction of recurrent AT/AF compared to the baseline clinical model, including LA LGE (C statistic 0.82 vs 0.77, P < .05 for both total LAEF and peak LA strain)., Conclusions: LA reservoir function was independently associated with recurrent AF/AT after PVI and can additionally improve risk stratification in patients undergoing PVI., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The extent of left atrial (LA) late gadolinium enhancement (LGE), as a surrogate for fibrosis, has been associated with atrial fibrillation (AF) recurrence after catheter ablation. Furthermore, there is ex vivo evidence that islands of fibrosis may anchor fibrillatory rotors., Objective: The purpose of this study was to examine the anatomical association of AF rotors with LA and right atrial (RA) LGE on cardiac magnetic resonance., Methods: The cohort included 9 patients with persistent AF (mean age 61.1 ± 9.7 years) who underwent LGE cardiac magnetic resonance before AF ablation using the focal impulse and rotor modulation system. The extent of LA and RA LGE was quantified globally and in each of the 7 sectors: LA posterior/inferior wall, anterior wall, roof, left and right pulmonary vein antra, and RA lateral and septal regions. The multivariable association of rotor incidence with global and per sector LGE extent was examined using multivariable Bernoulli logistic regression estimated by generalized estimating equations., Results: The mean RA and LA volumes were 113.2 ± 37.31 and 143.03 ± 58.25 mL, respectively. The mean RA and LA LGE burden was 17.2% ± 11.0% and 17.4% ± 14.4%, respectively. A total of 18 LA rotors and 9 RA rotors were identified in all patients. No univariable or multivariable association was observed between global or per sector LGE extent and focal impulse and rotor modulation rotor incidence., Conclusion: In this cohort of patients, there was no association between AF rotor incidence and the global or regional extent of RA and LA LGE., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)