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Background: Islets of myocytes within fibrofatty scars represent the substrate for reentrant ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC). Electroanatomic mapping can reliably identify such areas.Objective: To prospectively test the association between late and fragmented electrograms within scar and arrhythmic events in patients with ARVC.Methods: High-density right ventricle electroanatomic mapping was performed in 32 patients with ARVC without history of cardiac arrest or sustained ventricular arrhythmias. Standard definitions of electroanatomic scars and fragmented, isolated, and very late potentials were used. All patients received an implantable cardioverter-defibrillator for the primary prevention of sudden death.Results: After a mean follow-up of 25 ± 7 months, 12 (38%) patients received appropriate implantable cardioverter-defibrillator shock for sustained ventricular arrhythmias. With the exception of a higher rate of previous syncope (P = .053), patients with arrhythmic events at follow-up did not differ from those who remained free from arrhythmic events in terms of other clinical variables, including cardiac magnetic resonance findings. Electroanatomic scars were present in all patients. The distribution and extent of electroanatomic scars were similar in the 2 groups (38 ± 25 cm(2) vs 33 ± 20 cm(2); P = .51). However, patients with implantable cardioverter-defibrillator shock had a higher prevalence of fragmented electrograms (92% vs 20%; P <.001), of isolated late potentials (75% vs 20%; P = .004), and of very late potentials (67% vs 25%; P = .030). Fragmented electrograms were the only variable independently associated with arrhythmic events at follow-up (hazard ratio 21; P = .015).Conclusion: The presence of fragmented and delayed electrograms within the scar predicts arrhythmic events in ARVC. [ABSTRACT FROM AUTHOR]

Background: Remote magnetic navigation (RMN) has been reported as a feasible and safe mapping and ablation system for treatment of ventricular arrhythmias (VAs). However, the reported success rates have been limited with the 4- and 8-mm catheter tips.Objective: This study sought to report the results in a large series of consecutive patients undergoing radiofrequency (RF) catheter ablation of VAs using the RMN with the 3.5-mm magnetic open-irrigated-tip catheter (OIC).Methods: A total of 110 consecutive patients with a clinical history of left VA were included in the study. In all cases, an OIC was utilized for mapping and ablation. When ablation with the RMN catheters failed, a manual OIC was used to eliminate the VA. Postablation pacing maneuvers and isoproterenol were used to verify the inducibility of the VAs. Outcomes were compared with those of a group of 92 consecutive patients undergoing manual ablation by the same operator.Results: Mapping and ablation with the magnetic OIC were performed in all 110 patients with VA. Ischemic cardiomyopathy was present in 33 (30%), nonischemic in 14 (13%), and in 63 (57%) patients no structural heart disease was present. Endocardial mapping was performed in all patients, whereas both endocardial and epicardial mapping were performed in 36 (33%) patients. Compared with manual ablation, RMN was associated with a longer procedural time (2.9 +/- 1.2 hours vs. 3.3 +/- 1.1 hours, P = 0.004) and RF time (24 +/- 12 minutes vs. 33 +/- 18 minutes, P = 0.005), whereas fluoroscopic time was significantly shorter (35 +/- 22 minutes vs. 26 +/- 14 minutes, P = 0.033). During the procedures, crossover to manual ablation was required in 15 patients (14%). At 11.7 +/- 2.1 months of follow-up in the study group and 18.7 +/- 3.7 months in the manual ablation group, 85% and 86% (P = 0.817) of patients, respectively, were free of VA.Conclusion: This large series of consecutive patients demonstrates that OIC ablation using RMN is effective for the treatment of left VAs. [ABSTRACT FROM AUTHOR]

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: Recurrence during the 3-month blanking period after radiofrequency ablation of atrial fibrillation (AF) is typically not considered as a predictor for late recurrence., Objective: We investigated the significance of early recurrence as a risk factor for late recurrence in patients with AF receiving pulsed-field ablation (PFA)., Methods: Consecutive patients undergoing PFA were prospectively followed up for 1 year. All patients received isolation of pulmonary veins. Additional ablation procedures were performed per operator's discretion. After the procedure, all remained on their previously ineffective antiarrhythmic drugs (AADs) during the 2-month blanking period after which the AADs were discontinued. Early recurrence was defined as atrial arrhythmia of >30-second duration during the 3-month blanking period, and any recurrence beyond 3 months was considered as late recurrence., Results: A total of 337 patients undergoing PFA for AF were included. Early recurrence was recorded in 53 patients (15.7%): 10 in the first month, 12 in the second month, and 31 in the third month. Of the 10 patients having recurrence during the first month, 7 (70%) remained in sinus rhythm after cardioversion whereas 3 (30%) underwent a redo procedure because of late recurrence. At 1 year, all patients with recurrence in the second and third months experienced late recurrence; among these patients, 10 (83.3%) of 12 and 27 (87%) of 31 underwent a redo procedure and the remaining 6 patients were in sinus rhythm on AADs., Conclusion: In this consecutive series of patients with AF, early recurrence in the second or third month after the PFA procedure was associated with a high risk of late recurrence. Thus, blanking period could be redefined as 1 month after PFA., 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: Premature ventricular contraction (PVC) burden is a risk factor for heart failure and cardiovascular death in patients with structural heart disease. Long-term electrocardiographic monitoring can have a significant impact on PVC burden evaluation by further defining PVC distribution patterns., Objective: This study aimed to ascertain the optimal duration of electrocardiographic monitoring to characterize PVC burden and to understand clinical characteristics associated with frequent PVCs and nonsustained ventricular tachycardia in a large US cohort., Methods: Commercial data (iRhythm's Zio patch) from June 2011 to April 2022 were analyzed. Inclusion criteria were age >18 years, PVC burden ≥5%, and wear period ≥13 days. PVC burden cutoffs were determined on the basis of AHA/ACC/HRS guidelines for very frequent PVCs (10,000-20,000 during 24 hours). Patients were assigned to categories by PVC densities: low, <10%; moderate, 10% to <20%; and high, ≥20%. Mean measured error was assessed at baseline and daily until the wear period's end for overall PVC burden and different PVC densities., Results: Analysis of 106,705 patch monitors revealed a study population with mean age of 70.6 ± 14.6 years (33.6% female). PVC burden was higher in male patients and those >65 years of age. PVC burden mean error decreased from 2.9% at 24 hours to 1.3% at 7 days and 0.7% at 10 days. Number of ventricular tachycardia episodes per patient increased with increasing PVC burden (P < .0001)., Conclusion: Extending ambulatory monitoring beyond 24 hours to 7 days or more improves accuracy of assessing PVC burden. Ventricular tachycardia frequency and duration vary by initial PVC density, highlighting the need for prolonged cardiac monitoring., Competing Interests: Disclosures Luigi DiBiase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St Jude Medical and has received speaker honoraria from Medtronic, AtriCure, EPiEP, and Biotronik. Edward Gerstenfeld has served on advisory boards for Biosense Webster, Adagio Medical, and Boston Scientific; has received lecture honoraria from Medtronic, Biosense Webster, Abbott, and Boston Scientific; and has received a research grant from Abbott. Timm Dickfeld has served on advisory boards for Biosense Webster and InHeart and has received consulting honoraria from Impulse Dynamics. Nishant Verma has received speaker’s fees from Medtronic, Boston Scientific, Abbott, and Zoll. Ardit Kacorri, Lori Crosson, and Alan Wilk are employees of iRhythm Technologies. The other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Long-term oral anticoagulation is the mainstay therapy for thromboembolic (TE) prevention in patients with atrial fibrillation. However, left atrial appendage occlusion (LAAO) could be a safe alternative to direct oral anticoagulants (DOACs) in patients with a very high TE risk profile., Objective: The purpose of this study was to compare the safety and efficacy of LAAO vs DOACs in patients with atrial fibrillation at very high stroke risk (CHA 2 DS 2 -VASc [congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke or transient ischemic attack or thromboembolism, vascular disease, age 65-74 years, sex category] score ≥ 5)., Methods: Data from patients with CHA 2 DS 2 -VASc score ≥ 5 were extracted from a prospective multicenter database. To attenuate the imbalance in covariates between groups, propensity score matching was used (covariates: CHA 2 DS 2 -VASc and HAS-BLED [hypertension, abnormal renal or liver function, stroke, bleeding, labile international normalized ratio, elderly, drugs or alcohol] scores), which resulted in a matched population of 277 patients per group. The primary end point was a composite of cardiovascular death, TE events, and clinically relevant bleeding during follow-up., Results: Of 2381 patients, 554 very high risk patients were included in the study (mean age 79 ± 7 years; CHA 2 DS 2 -VASc score 5.8 ± 0.9; HAS-BLED score 3.0 ± 0.9). The mean follow-up duration was 25 ± 11 months. A higher incidence of the composite end point was documented with DOACs compared with LAAO (14.9 events per 100 patient-years in the DOAC group vs 9.4 events per 100 patient-years in the LAAO group; P = .03). The annualized clinically relevant bleeding risk was higher with DOACs (6.3% vs 3.2%; P = .04), while the risk of TE events was not different between groups (4.1% vs 3.2%; P = .63)., Conclusion: In high-risk patients, LAAO had a similar stroke prevention efficacy but a significantly lower risk of clinically relevant bleeding when compared with DOACs. The clinical benefit of LAAO became significant after 18 months of follow-up., Competing Interests: Disclosures Dr Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr Chierchia has received compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, Boston Scientific, and Acutus Medical. Dr de Asmundis has received research grants on behalf of the center from Biotronik, Medtronic, Abbott, LivaNova, Boston Scientific, AtriCure, Philips, and Acutus Medical and compensation for teaching purposes and proctoring from Medtronic, Abbott, Biotronik, LivaNova, Boston Scientific, AtriCure, Acutus Medical, and Daiichi Sankyo. Dr Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical. Dr Di Biase has received speaker honoraria/travel support from Medtronic, Bristol Meyers Squibb, Pfizer, and Biotronik. Dr Natale has received speaker honoraria from Boston Scientific, Biosense Webster, St. Jude Medical, Biotronik, and Medtronic and is a consultant for Biosense Webster, St. Jude Medical, and Janssen. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Limited data are available on leadless pacemaker (LPM) outcomes according to different stages of chronic kidney disease (CKD)., Objective: The purpose of this study was to investigate differences in the safety and efficacy of LPMs among patients stratified per different stages of renal function., Methods: Consecutive patients enrolled in the multicenter international i-LEAPER registry (International LEAdless PacemakEr Registry) were analyzed. Patients were divided into 3 groups according to CKD stage. The primary end point was the comparison of LPM-related major complication rate at implantation and during follow-up. Differences in electrical performance were deemed secondary outcomes., Results: Of the 1748 patients enrolled, 33% were in CKD stage G3a/G3b and 9.4% were in CKD stage G4/G5. Patients with CKD presented cardiovascular comorbidities more frequently. During a median follow-up of 39 months (interquartile range [IQR] 18-59 months), major complication rate did not differ between groups (normal kidney function [NKF] group 1.8% vs CKD stage G3a/G3b group 2.9% vs CKD stage G4/G5 group 2.4%; P = .418). All-cause mortality resulted higher in the CKD stage G4/G5 group than in the NKF group (19.5% vs 9.8%; adjusted hazard ratio 1.9; 95% confidence interval 1.25-2.89; P = .003). LPM electrical performance was comparable between groups, except for patients with CKD who showed a slightly higher pacing threshold during 1-month follow-up (NKF group 0.50 V [IQR 0.35-0.70 V] vs G3a/G3b group 0.56 V [IQR 0.38-0.81 V] vs G4/G5 group 0.51 V [0.38-0.84 V] @ 0.24 ms; P < .001)., Conclusion: In a real-world setting, patients with advanced CKD who underwent LPM implantation were underrepresented. Although all-cause mortality was higher in end-stage CKD, periprocedural complications and LPM performance were overall comparable between NKF and different stages of CKD, except for higher values of pacing threshold in patients with CKD up to first-month follow-up., Competing Interests: Disclosures Dr Tondo is a member of an advisory board of Medtronic. Other authors do not report disclosures regarding this article., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: After a cryptogenic stroke, patients often will require prolonged cardiac monitoring; however, the subset of patients who would benefit from long-term rhythm monitoring is not clearly defined., Objective: The purpose of this study was to create a risk score by identifying significant predictors of atrial fibrillation (AF) using age, sex, comorbidities, baseline 12-lead electrocardiogram, short-term rhythm monitoring, and echocardiographic data and to compare it to previously published risk scores., Methods: Patients admitted to Montefiore Medical Center between May 2017 and June 2022 with a primary diagnosis of cryptogenic stroke or transient ischemic attack who underwent long-term rhythm monitoring with an implantable cardiac monitor were retrospectively analyzed., Results: Variables positively associated with a diagnosis of clinically significant AF include age (P <.001), race (P = .022), diabetes status (P = .026), chronic obstructive pulmonary disease status (P = .012), presence of atrial runs (P = .003), number of atrial runs per 24 hours (P <.001), total number of atrial run beats per 24 hours (P <.001), number of beats in the longest atrial run (P <.001), left atrial enlargement (P = .007), and at least mild mitral regurgitation (P = .009). We created a risk stratification score for our population, termed the ACL score. The ACL score demonstrated superiority to the CHA 2 DS 2 -VASc score and comparability to the C 2 HEST score for predicting device-detected AF., Conclusion: The ACL score enables clinicians to better predict which patients are more likely to be diagnosed with device-detected AF after a cryptogenic stroke., Competing Interests: Disclosures Dr Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical; and has received speaker honoraria from Medtronic, AtriCure, EPiEP, and Biotronik. The other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

The complexity of cardiac electrophysiology procedures has increased significantly during the past 3 decades. Anesthesia requirements of these procedures can differ on the basis of patient- and procedure-specific factors. This manuscript outlines various anesthesia strategies for cardiac implantable electronic devices and electrophysiology procedures, including preprocedural, procedural, and postprocedural management. A team-based approach with collaboration between cardiac electrophysiologists and anesthesiologists is required with careful preprocedural and intraprocedural planning. Given the recent advances in electrophysiology, there is a need for specialized cardiac electrophysiology anesthesia care to improve the efficacy and safety of the procedures., (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.)

Competing Interests: Disclosures Dr Di Biase is a consultant for Biosense Webster, Boston Scientific, Stereotaxis, and St. Jude Medical; and has received speaker honoraria from Medtronic, AtriCure, EPiEP, and Biotronik. Dr Natale is a consultant for Biosense Webster, Stereotaxis, and Abbott Medical; and has received speaker honoraria/travel from Medtronic, AtriCure, Biotronik, and Janssen. All other authors have no conflicts of interest to disclose.

Background: The impact of sex in clinical and procedural outcomes in leadless pacemaker (LPM) patients has not yet been investigated., Objective: The purpose of this study was to investigate sex-related differences in patients undergoing LPM implantation., Methods: Consecutive patients enrolled in the i-LEAPER registry were analyzed. Comparisons between sexes were performed within the overall cohort using an adjusted analysis with 1:1 propensity matching for age and comorbidities. The primary outcome was the comparison of major complication rates. Sex-related differences regarding electrical performance and all-cause mortality during follow-up were deemed secondary outcomes., Results: In the overall population (n = 1179 patients; median age 80 years), 64.3% were men. After propensity matching, 738 patients with no significant baseline differences among groups were identified. During median follow-up of 25 [interquartile range 24-39] months, female sex was not associated with LPM-related major complications (hazard ratio [HR] 2.03; 95% confidence interval [CI] 0.70-5.84; P = .190) or all-cause mortality (HR 0.98; 95% CI 0.40-2.42; P = .960). LPM electrical performance results were comparable between groups, except for a higher pacing impedance in women at implant and during follow-up (24 months: 670 [550-800] Ω vs 616 [530-770] Ω; P = .014) that remained within normal limits., Conclusion: In a real-world setting, we found differences in sex-related referral patterns for LPM implantation with an underrepresentation of women, although major complication rate and LPM performance were comparable between sexes. Female patients showed higher impedance values, which had no impact on overall device performance. Electrical parameters remained within normal limits in both groups during the entire follow-up., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: General anesthesia (GA) is the standard anesthetic approach for subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. Nonetheless, GA is expensive and can be associated with adverse events. Tumescent local anesthesia (TLA) has been shown to reduce in-room and procedural times and to decrease post-procedural pain, all of which could result in a reduction in procedure-related costs., Objective: The purpose of this study is to compare the cost-effectiveness of GA and TLA in patients undergoing S-ICD implantation., Methods: The present study is a prospective, nonrandomized, controlled study of patients who underwent S-ICD implantation between 2019 and 2022. Patients were allocated to either the TLA or the GA group. We performed a cost analysis for each intervention. As an effectiveness measure, the 0-10 point Numeric Pain Rating Scale at 1, 12, and 24 hours post-implantation was analyzed and compared between the groups. A score of 0 was considered no pain; 1-5, mild pain; 6-7, moderate pain; and 8-10, severe pain. Cost-effectiveness was calculated using incremental cost-effectiveness ratios., Results: Seventy patients underwent successful S-ICD implantation. The total cost of the electrophysiology laboratory was higher in the GA group than in the TLA group (median ± interquartile range US$55,824 ± US$29,411 vs US$37,222 ± US$24,293; P < .001), with a net saving of $20,821 when compared with GA for each S-ICD implantation. There was a significant decrease in post-procedural pain scores in the TLA group when compared with the GA group (repeated measures analysis of variance, P = .009; median ± interquartile range 0 ± 3 vs 0 ± 5 at 1 hour, P = .058; 3 ± 4 vs 6 ± 8 at 12 hours, P = .030; 0 ± 4 vs 2 ± 6 at 24 hours, P = .040)., Conclusion: TLA is a more cost-effective alternative to GA for S-ICD implantation, with both direct and indirect cost reductions. Importantly, these reduced costs are associated with reduced postprocedural pain., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Medical treatment of inappropriate sinus tachycardia (IST) remains suboptimal. Radiofrequency sinus node (RF-SN) ablation has poor success and higher complication rates., Objective: We aimed to compare clinical outcomes of the novel SN sparing hybrid ablation technique with those of RF-SN modification for IST management., Methods: This is a multicenter prospective registry comparing the SN sparing hybrid ablation strategy with RF-SN modification. The hybrid procedure was performed using an RF bipolar clamp, isolating superior vena cava/inferior vena cava with the creation of a lateral line across the crista terminalis while sparing the SN region (identified by endocardial 3-dimensional mapping). RF-SN modification was performed by endocardial and/or epicardial mapping and ablation at the site of earliest atrial activation., Results: Of the 100 patients (hybrid ablation group, n = 50; RF-SN group, n = 50), 82% were women, and the mean age was 22.8 years. Normal sinus rhythm and rate were restored in all patients in the hybrid group (vs 84% in the RF-SN group; P = .006). Hybrid ablation was associated with significantly better improvement in mean daily heart rate and peak 6-minute walk heart rate compared with RF-SN ablation. The RF-SN group had a significantly higher rate of redo procedures (100% vs 8%; P < .001), phrenic nerve injury (14% vs 0%; P = .012), lower acute pericarditis (48% vs 92%; P < .0001), permanent pacemaker implantation (50% vs 4%; P < .0001) than did the hybrid ablation group., Conclusion: The novel sinus node sparing hybrid ablation procedure appears to be more efficacious and safer in patients with symptomatic drug-resistant IST with long-term durability than RF-SN ablation., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Ventricular arrhythmias (VAs) represent a critical issue with regard to sports eligibility assessment in athletes. The ideal diagnostic evaluation of competitive and leisure-time athletes with complex VAs has not been clearly defined., Objective: The purpose of this study was to assess the clinical implications of invasive electrophysiological assessments and endomyocardial biopsy (EMB) among athletes with VAs., Methods: We evaluated 227 consecutive athletes who presented to our institutions after being disqualified from participating in sports because of VAs. After noninvasive tests, electrophysiological study (EPS), electroanatomic mapping (EAM), and EAM- or cardiac magnetic resonance imaging-guided EMB was performed, following a prespecified protocol. Sports eligibility status was redefined at 6-month follow-up., Results: From our sample, 188 athletes (82.8%) underwent EAM and EPS, and 42 (15.2%) underwent EMB. A diagnosis of heart disease could be formulated in 30% of the study population (67/227; 95% confidence interval [CI] 0.24-0.36) after noninvasive tests; in 37% (83/227; 95% CI 31%-43%) after EPS and EAM; and in 45% (102/227; 95% CI 39%-51%) after EMB. In the subset of athletes undergoing EMB, invasive diagnostic workup allowed diagnostic reclassification of half of the athletes (n = 21 [50%]). Reclassification was particularly common among subjects without definitive findings after noninvasive evaluation (n = 23; 87% reclassified). History of syncope, abnormal echocardiogram, presence of late gadolinium enhancement, and abnormal EAM were linked to sports ineligibility at 6-month follow-up., Conclusion: A comprehensive invasive workup provided additional diagnostic elements and could improve the sports eligibility assessment of athletes presenting with VAs. The extensive invasive evaluation presented could be especially helpful when noninvasive tests show unclear findings., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: To date, only a few comparisons between subcutaneous implantable cardioverter-defibrillator (S-ICD) patients undergoing and those not undergoing defibrillation testing (DT) at implantation (DT+ vs DT-) have been reported., Objective: The purpose of this study was to compare long-term clinical outcomes of 2 propensity-matched cohorts of DT+ and DT- patients., Methods: Among consecutive S-ICD patients implanted across 17 centers from January 2015 to October 2020, DT- patients were 1:1 propensity-matched for baseline characteristics with DT+ patients. The primary outcome was a composite of ineffective shocks and cardiovascular mortality. Appropriate and inappropriate shock rates were deemed secondary outcomes., Results: Among 1290 patients, a total of 566 propensity-matched patients (283 DT+; 283 DT-) served as study population. Over median follow-up of 25.3 months, no significant differences in primary outcome event rates were found (10 DT+ vs 14 DT-; P = .404) as well as for ineffective shocks (5 DT- vs 3 DT+; P = .725). At multivariable Cox regression analysis, DT performance was associated with a reduction of neither the primary combined outcome nor ineffective shocks at follow-up. A high PRAETORIAN score was positively associated with both the primary outcome (hazard ratio 3.976; confidence interval 1.339-11.802; P = .013) and ineffective shocks alone at follow-up (hazard ratio 19.030; confidence interval 4.752-76.203; P = .003)., Conclusion: In 2 cohorts of strictly propensity-matched patients, DT performance was not associated with significant differences in cardiovascular mortality and ineffective shocks. The PRAETORIAN score is capable of correctly identifying a large percentage of patients at risk for ineffective shock conversion in both cohorts., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Subcutaneous implantable cardioverter-defibrillator (S-ICD) is an effective alternative to transvenous implantable cardioverter-defibrillator. General anesthesia (GA) is considered the standard sedation approach because of the pain caused by the manipulation of subcutaneous tissue with S-ICD implantation. However, GA carries several limitations, including additional risk of adverse events, prolonged in-room times, and increased costs., Objective: The purpose of this study was to define the effectiveness and safety of tumescent local anesthesia (TLA) in comparison to GA in patients undergoing S-ICD implantation., Methods: We performed a prospective, nonrandomized, controlled, multicenter study of patients referred for S-ICD implantation between 2019 and 2020. Patients were allocated to either TLA or GA on the basis of patient's preferences and/or anesthesia service availability. TLA was prepared using lidocaine, epinephrine, sodium bicarbonate, and sodium chloride. All patients provided written informed consent, and the institutional review board at each site provided approval for the study., Results: Sixty patients underwent successful S-ICD implantation from July 2019 to November 2020. Thirty patients (50%) received TLA, and the rest GA. There were no differences between groups with regard to baseline characteristics. In-room and procedural times were significantly shorter with TLA (107.6 minutes vs 186 minutes; P < .0001 and 53.2 minutes vs 153.7 minutes; P < .0001, respectively). Pain was reported less frequently by patients who received TLA. The use of opioids was significantly reduced in patients who received TLA (23% vs 62%; P = .002)., Conclusion: TLA is an effective and safe alternative to GA in S-ICD implantation. The use of TLA is associated with shorter in-room and procedural times, less postprocedural pain, and reduced usage of opioids and acetaminophen for analgesia., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the authors. The authors inadvertently specified some ablation settings in the methods section that should not have been reported because they can be potentially linked to a specific pulsed field ablation technology that is currently under investigation for FDA approval. The Authors apologize for the inconvenience caused by this oversight, http://dx.doi.org/., (Copyright © 2021. Published by Elsevier Inc.)

Background: Substrate catheter ablation of scar-related ventricular tachycardia (VT) is a widely accepted therapeutic option for patients with ischemic cardiomyopathy (ICM)., Objective: The purpose of this study was to investigate whether concomitant amiodarone therapy affects procedural outcomes., Methods: A total of 134 consecutive patients (89% male; age 66 ± 10 years) with ICM undergoing catheter ablation of VT were included in the study. Patients were sorted by amiodarone therapy before ablation. In all patients, a substrate-based catheter ablation (endocardial ± epicardial) in sinus rhythm abolishing all "abnormal" electrograms within the scar was performed. The endpoint of the procedure was VT noninducibility. After the ablation procedure, all antiarrhythmic medications were discontinued. All patients had an implantable cardioverter-defibrillator, and recurrences were analyzed through the device., Results: In 84 patients (63%), the ablation was performed on amiodarone; the remaining 50 patients (37%) were off amiodarone. Patients had comparable baseline characteristics. Mean scar size area was 143.6 ± 44.9 cm 2 on amiodarone vs 139.2 ± 36.8 cm 2 off amiodarone (P = .56). More radiofrequency time was necessary to achieve noninducibility in the off-amiodarone group compared to the on-amiodarone group (68.1 ± 20.1 minutes vs 51.5 ± 19.7 minutes; P <.001). In addition, due to persistent VT inducibility, more patients in the off-amiodarone group required epicardial ablation than in the on-amiodarone group (13/50 [26%] vs 5/84 [6%], respectively; P <.001). During mean follow-up of 23.9 ± 11.6 months, recurrence of any ventricular arrhythmias off antiarrhythmic drugs was 44% (37/84) in the on-amiodarone group vs 22% (11/50) in the off-amiodarone group (P = .013)., Conclusion: Albeit, VT noninducibility after substrate catheter ablation for scar related VT was achieved faster, with less radiofrequency time and less need for epicardial ablation in patients taking amiodarone, these patients had significantly higher VT recurrence at long-term follow-up when this medication was discontinued., (Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Multiple studies have addressed the importance of anteroseptal scar in patients with nonischemic cardiomyopathy. However, this pattern has never been fully evaluated in patients with prior myocarditis., Objective: The purpose of this study was to evaluate whether anteroseptal scar is associated with worse outcome in patients with prior myocarditis and how it affects the efficacy of catheter ablation (CA)., Methods: This was a retrospective study of consecutive patients with prior myocarditis and arrhythmic presentation. Cardiac magnetic resonance and electroanatomic voltage mapping were used to identify the scar pattern. Patients were referred for either CA or escalated antiarrhythmic drug (AAD) therapy. The main outcome was ventricular arrhythmia (VA)-free survival according to the presence of anteroseptal scar., Results: A total of 144 consecutive patients with prior myocarditis were included. Mean age was 42.1 ± 14.9 years, and 58% were men. Ejection fraction was normal in 73% of patients. Anteroseptal scar was present in 44% of cases. Sixty-one patients (42%) underwent CA. Overall, at 2-year follow-up, VA-free survival was 77% in the CA group. After CA, the mean number of AADs taken by each patient decreased from 1.8 to 0.9 per day (p<0.001). The presence of anteroseptal scar was found to be an independent predictor of VA relapse both in patients treated with CA (hazard ratio [HR] 3.6; 95% confidence interval [CI] 1.1-11.4; P = .03) and in the overall population (HR 2.0; 95% CI 1.2-3.5; P = .02) ., Conclusion: In patients with prior myocarditis and VA, the presence of anteroseptal scar negatively predicts outcomes irrespective of treatment strategy., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Thromboembolic stroke is a rare but devastating consequence of atrial fibrillation (AF) ablation. Transesophageal echocardiography (TEE) is recommended to rule out left atrial appendage thrombus; however, its use is variable., Objective: The purpose of this study was to assess whether TEE is mandatory in patients undergoing AF ablation on uninterrupted direct oral anticoagulants (DOACs)., Methods: Data from our prospective multicenter registry of patients with AF undergoing radiofrequency catheter ablation on uninterrupted DOACs were analyzed. All the included patients were on anticoagulation for at least 4 weeks before ablation. All AF ablation procedures were performed under intracardiac echocardiography guidance. Before transseptal puncture, heparin bolus was administered, followed by continuous infusion, with a target activated clotting time of >300 seconds., Results: A total of 6186 patients (3180 on apixaban [51.4%], 2528 on rivaroxaban [40.9%], 404 on dabigatran [6.5%], and 74 on edoxaban [1.2%]) were analyzed. The mean age of the study population was 69.4 ± 10.3 years; 4194 patients (67.8%) were male, and 5120 patients (82.8%) had persistent and long-standing persistent AF. The mean CHA 2 DS 2 -VASc score was 2.86 ± 1.58; the mean CHADS 2 score was 1.65 ± 1.14. Intracardiac echocardiography ruled out left atrial appendage and left atrial thrombi in all patients and revealed "smoke" in 1672 patients (27.03%). Transient ischemic attack was noted in 1 patient with long-standing persistent AF in the setting of a missed dose of rivaroxaban before ablation., Conclusion: Our study showed that performing AF ablation in patients on uninterrupted DOACs without TEE is safe and feasible in high stroke risk patients. Elimination of routine preablation TEE would have significant economic and clinical implications., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Premature ventricular contractions (VPC) have hour-to-hour and day-to-day variation. High VPC burden correlates with cardiomyopathy., Objective: To determine the optimal duration for ambulatory electrocardiogram monitoring for accurate assessment of VPC burden., Methods: Our group performed a retrospective analysis on patch monitors used for any indication with overall VPC burden ≥5.0% between February 1, 2016, and February 1, 2020. We generated cumulative daily VPC averages for each day of wear and performed linear regression analysis between each cumulative daily average and overall burden. Patients were divided into groups based on low or high VPC frequency, and the analysis was repeated. Split-sample validation was used to internally validate the overall prediction model., Results: A total of 116 patches representing 107 patients (mean age: 64.5; female: 48%) were analyzed. Mean overall VPC burden was 13.4% ± 7.5% (range: 5.0%-42.0%). Day 1 R 2 was 60%, P < .001, and continued to increase to R 2 88%, P < .001 at day 14. Median percent and absolute error decreased from 22.70% (interquartile range [IQR]: 9.73-34.39) and 2.58% (IQR: 1.24-4.59) at day 1 to 5.62% (IQR: 2.82-8.39) and 0.55% (IQR: 0.28-1.05) at day 14. Patients with higher overall VPC frequencies achieved a more rapid rise in R 2 relative to those with lower frequencies. Split-sample validation supported the internal validity of our linear regression prediction model., Conclusion: Mobile telemetry for a period of ∼7 days accurately reflects overall VPC burden. Measurement of VPC burden for only 24-48 hours may not accurately reflect total burden. Monitoring for 2 weeks or longer adds little additional VPC information., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Epicardial mapping and ablation are frequently necessary to eliminate ventricular tachycardia (VT) in patients with Chagas disease. Nonetheless, there are no randomized controlled trials demonstrating the role of this strategy., Objective: We conducted this randomized controlled trial to evaluate the efficacy and safety of combined epicardial ablation in patients with Chagas disease., Methods: We randomized patients with Chagas disease and VT in a 1:1 fashion to either the endocardial (endo) mapping and ablation group or the combined endocardial/epicardial (endo/epi) mapping and ablation group. The efficacy end points were measured by VT inducibility and all-ventricular arrhythmia recurrence. Safety was assessed by the rate of periprocedural complications., Results: Thirty patients were enrolled, and most were male. The median age was 67 (Q1: 58; Q3: 70) years in the endo group and 58 (Q1: 43; Q3: 66) years in the endo/epi group. The left ventricular ejection fraction was 33.0% ± 9.5% and 35.2% ± 11.5%, respectively P = .13. Acute success (non-reinducibility of clinical VT) was obtained in 13 patients (86%) in the endo/epi group and in 6 patients (40%) in the endo-only group (P = .021). There were 12 patients with VT recurrence (80%) in the endo-only group and 6 patients (40%) in the endo/epi group (P = .02) (by intention-to-treat analysis). Epicardial ablation was ultimately performed in 9 patients (60%) in the endo-only group because of an absence of endocardial scar or maintenance of VT inducibility. There was no difference in complications between the groups., Conclusion: Combining endo/epi VT catheter ablation in patients with Chagas disease significantly increases short- and long-term freedom from all-ventricular arrhythmias. Epicardial access did not increase periprocedural complication rates., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Single-chamber leadless pacemakers (LPs) have been shown to be an effective alternative to conventional transvenous pacemakers (CTPs), but their benefit in the context of cardioinhibitory vasovagal syncope (CI-VVS) is unknown., Objective: The purpose of this study was to evaluate the safety and efficacy of LP compared with dual-chamber CTP for CI-VVS., Methods: We conducted a multicenter, retrospective study comparing patients who received LP or dual-chamber CTP for drug-refractory CI-VVS. CI-VVS was diagnosed clinically and supported by cardiac monitoring and head-up tilt table testing. The primary efficacy endpoint was freedom from syncope during follow-up. Secondary endpoints included device efficacy and safety estimated by device-related major and minor adverse events (AEs)., Results: Seventy-two patients (24 LP, 48 CTP; age 32 ± 5.5 years; 90% female; syncope frequency 7.6 ± 3.4 per year) were included. At 1 year, 91% of patients (22/24) in the LP group and 94% of patients (43/48) in the CTP group met the primary efficacy endpoint (P = .7). Device efficacy endpoint was met in 92% of the LP group and 98% of the CTP group (P = .2). Early major AEs occurred in 2 of 24 in the LP group and 3 of 48 in the CTP group (P = .4). Late major AEs occurred in 0 of 24 in the LP group and 2 of 48 in the CTP group (P = 1)., Conclusion: In patients with CI-VVS, single-chamber LP demonstrated equivalent efficacy in reducing syncopal events compared to dual-chamber CTP, with a similar safety profile., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Managing arrhythmias from the left ventricular summit and interventricular septum is a major challenge for the clinical electrophysiologist requiring intimate knowledge of cardiac anatomy, advanced training and expertise. Novel mapping and ablation strategies are needed to treat arrhythmias originating from these regions given the current suboptimal long-term success rates with standard techniques. Herein, we describe innovative approaches to improve acute and long-term clinical outcomes such as mapping and ablation using the septal coronary venous system and the septal coronary arteries, alcohol ablation, coil embolization, and ablation of all early sites among others., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Disease progression and ventricular arrhythmias (VAs) in arrhythmogenic right ventricular cardiomyopathy (ARVC) are correlated with physical exercise, and clinical detraining and avoidance of competitive sport practice are suggested for ARVC patients. An algorithm assessing primary arrhythmic risk in ARVC patients was recently developed by Cadrin-Tourigny et al. Data regarding its transferability to athletes are lacking., Objective: The purpose of this study was to assess the reliability of the Cadrin-Tourigny risk prediction algorithm in a cohort of athletes with ARVC and to describe the impact of clinical detraining on disease progression., Methods: All athletes undergoing clinical detraining after ARVC diagnosis at our institution were enrolled. Baseline and follow-up clinical characteristics and data on VA events occurring during follow-up were collected. The Cadrin-Tourigny algorithm was used to calculate the a priori predicted VA risk, which was compared with the observed outcomes., Results: Twenty-five athletes (age 36.1 ± 14.0 years; 80% male) with definite ARVC who were undergoing clinical detraining were enrolled. Over median (interquartile range) follow-up of 5.3 (3.2-6.6) years, a reduction in premature ventricular complex (PVC) burden (P = .001) was assessed, and 10 VA events (40%) were recorded. The a priori algorithm-predicted risk seemed to fit with the observed cohort arrhythmic risk [mean observed-predicted risk difference over 5 years -0.85% (interquartile range -4.8% to +3.1%); P = .85]. At 1-year follow-up, 11 patients (44%) had an improved stress ECG response, and no significant changes in right ventricular ejection fraction were observed., Conclusion: Clinical detraining is associated with PVC burden reduction in athletes with ARVC. The novel risk prediction algorithm does not seem to require any correction for its application to ARVC athletes., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: A significant role of the left atrial appendage (LAA) in the genesis of atrial fibrillation (AF) has been described. Left atrial appendage electrical isolation (LAAEI) confers substantial long-term clinical benefits. Nevertheless, the left phrenic nerve (LPN) is in the vicinity of the LAA and can be injured during radiofrequency ablation at the ostial level., Objective: The purpose of this study was to describe our experience mapping the LPN, its anatomic relationships to the LAA and alternative approaches to isolate this structure when the LPN is located at the LAA ostium., Methods: Patients undergoing LAAEI for nonparoxysmal AF were included in this study. We attempted to localize the LPN with high-output pacing (20 mA/2 ms). Cases were classified into 4 groups (distal, middle, proximal segment and unmappable) based on the position of the LPN in electroanatomic mapping in the posterior wall of the LAA., Results: A total of 66 cases were included in this study. The LPN was mapped in the distal segment in 27 cases (40.9%); in the middle segment in 22 (33.3%); and at the proximal segment/ostium in 3 (4.5%); the LPN was unmappable in 14 cases (21.2%). In the 3 patients in whom the LPN was at the ostial level or crossing the ostium, segmental LAAEI was attempted in 2, with successful LAAEI achieved in 1 case. There was no LPN injury., Conclusion: LPN mapping is feasible and should be routinely performed to prevent LPN injury during LAAEI., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The electrocardiogram (ECG) is essential for the differential diagnosis of wide QRS complex tachycardia (WCT)., Objective: The purpose of this study was to evaluate the diagnostic value of a novel ECG algorithm on the basis of the morphological characteristics of the QRS on the limb leads., Methods: The limb lead algorithm (LLA) was evaluated by analyzing 528 monomorphic WCTs with electrophysiology-confirmed diagnoses. In the LLA, ventricular tachycardia (VT) is diagnosed in the presence of at least 1 of the following: (1) monophasic R wave in lead aVR; (2) predominantly negative QRS in leads I, II, and III; and (3) opposing QRS complex in the limb leads: concordant monophasic QRS in all 3 inferior leads and concordant monophasic QRS in 2 or 3 of the remaining limb leads with a polarity opposite to that of the inferior leads. The diagnostic performance of the LLA was compared with that of the Brugada, Vereckei, and R-wave peak time (RWPT) algorithms., Results: Of 528 WCT cases, 397 were VT and 131 supraventricular tachycardia. The interobserver agreement for the LLA was excellent (κ = 0.98), better than that for the other algorithms. The overall accuracy of the LLA (88.1%) was similar to that of Brugada (85.4%) and Vereckei (88.1%) algorithms but was higher than that of the RWPT algorithm (70.8%). The LLA had a lower sensitivity (87.2%) than did Brugada (94.0%) and Vereckei (92.4%) algorithms, but not the RWPT algorithm (67.8%). Furthermore, the LLA showed a higher specificity (90.8%) than did Brugada (59.5%), Vereckei (76.3%), and RWPT (80.2%) algorithms., Conclusion: The LLA is a simple yet accurate method to diagnose VT when approaching WCTs on the ECG., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Percutaneous left atrial appendage (LAA) occlusion with Lariat has emerged as a viable alternative to oral anticoagulation (OAC) to prevent thromboembolic (TE) events in patients with atrial fibrillation., Objective: We evaluated the long-term TE risk in post-Lariat patients., Methods: Consecutive patients undergoing LAA ligation with the Lariat device at multiple centers with at least 1-year follow-up were included in the analysis. Transesophageal echocardiography (TEE) was performed at 4 weeks, 6 months, and 12 months to assess the completeness of LAA occlusion. OAC was discontinued if 4-week TEE revealed no device-related thrombus and complete closure of the appendage. Patients remained on 81 mg of aspirin per day after discontinuation of the blood thinner., Results: A total of 306 patients were included in the study (mean age 68.8 ± 11.0 years; mean CHA 2 DS 2 -VASc score 3.6 ± 1.7). Four-week TEE revealed leaks in 81 patients (26.5%); all leaks were less than 5 mm in diameter. At 6-month TEE, spontaneous closure of the leak was demonstrated in 21 patients (25.9%), 26 patients (32%) underwent a successful leak closure procedure, and the remaining 34 (42%) patients were placed on OAC. At the median follow-up period of 15.9 ± 9.2 months, 9 TE events (2.9%) were reported: 7 with persistent leak and 2 without any detectable leaks on 2-dimensional TEE (P < .001)., Conclusion: Complete occlusion of the LAA with the Lariat device was associated with the low rate of TE events at long-term follow-up. However, residual leaks were common after Lariat closure and the stroke rate was significantly higher in patients with incomplete occlusion, even with small leaks., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Fragmented QRS (fQRS) on 12-lead electrocardiography is a noninvasive marker of intramyocardial conduction delay due to ventricular scarring that has not previously been studied in atrial fibrillation., Objective: The purpose of this study was to assess the association of fQRS with left atrial (LA) scarring in patients with persistent atrial fibrillation (PsAF) undergoing first catheter ablation., Methods: A total of 376 patients with PsAF were enrolled. Severity of LA scarring was assessed using electroanatomic mapping. Narrow fQRS was defined by the presence of an additional R wave (R') or notching in the nadir of the S wave, or the presence of >1 R' in 2 contiguous leads corresponding to inferior, lateral, or anterior myocardial regions., Results: Both any degree (97.3% vs 63.3%) and severe (42.2% vs 6.3%) LA scarring were higher in patients with fQRS. Age and fQRS were found to be independent predictors of severe LA scarring. At multiple ventricular regions, fQRS had diagnostic accuracy of 79.8% for prediction of severe LA scarring. Nonpulmonary vein triggers were more often detected and ablated in patients with fQRS and severe LA scarring (84.4% vs 70%; P = .001). Atrial tachyarrhythmia recurrence was observed in 131 patients (34.8%) during 18.9 ± 7.7 months of follow-up, which was significantly higher in patients with fQRS (53.2% vs 16.8%). In multivariate analysis, fQRS was found to be a significant predictor of recurrence (hazard ratio 4.65; 95% interval confidence 2.91-7.42; P <.001)., Conclusion: The study results showed that fQRS is a simple, available, and noninvasive marker, and that fQRS at multiple ventricular regions is significantly associated with the severity of LA scarring in PsAF patients., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Access to the epicardial space is fundamental to several cardiac procedures. While traditional indications include catheter ablation of ventricular arrhythmias and accessory pathways, novel indications include left atrial appendage occlusion, esophageal protection, mapping and ablation during atrial fibrillation procedures, implantation of epicardial pacing leads, and phrenic nerve displacement to facilitate safe ablation of atrial and ventricular arrhythmias. Accessing the epicardial space safely is a major challenge requiring intimate knowledge of cardiac anatomy, extensive training, and expertise. Over the past years, multiple technological advances have led to significant improvements in epicardial access success and safety. Important examples of such advances include CO 2 insufflation through the coronary sinus or the right atrial appendage, pressure sensor needle, computed tomography, cardiac magnetic resonance, and electroanatomic mapping-guided epicardial access. In addition, we provide special maneuvers to minimize inadvertent right ventricular perforation., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) triggers within the coronary sinus (CS)/great cardiac vein (GCV) and the left atrial appendage (LAA) have been recognized as nonpulmonary vein triggers of AF., Objective: The aim of this study was to describe an electrical connection between the LAA and CS/GCV and its importance in achieving LAA electrical isolation (LAAEI)., Methods: A total of 488 consecutive patients undergoing catheter ablation for persistent or long-standing persistent AF who showed firing from the LAA and/or from the CS/GCV were enrolled in this multicenter prospective study. In all patients, potential defragmentation of the CS/GCV to achieve isolation and LAAEI was attempted with both endocardial and epicardial ablation., Results: In 7% (n = 34) of these patients, after attempting endocardial LAAEI, the LAA was isolated during epicardial ablation in the GCV. In 8% (n = 39) of patients after attempting endocardial LAA isolation, the LAA was isolated during ablation along the endocardial aspect of the GCV. The presence of a venous branch connecting the GCV with the LAA was found in all these patients. In 23% (n = 112) of patients, the isolation of the LAA also isolated the GCV. In all these patients, LAA dissociated firing was present together with the CS/GCV recordings., Conclusion: These findings suggest the presence of a distinct electrical connection between the GCV and the LAA. The clinical relevance of our results requires further investigation. Ablation in the CS/GCV can result in inadvertent isolation of the LAA. Ablation of the GCV is relevant to achieve LAAEI. Considering the potential long-term implications, ablation in the distal CS/GCV should prompt assessment of LAA conduction., (Copyright © 2019 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The optimal site of ablation of idiopathic left ventricular outflow tract (LVOT) ventricular arrhythmias (VAs) is challenging as activation mapping can reveal similar activation times in different anatomical sites, suggesting an intramural origin., Objective: We sought to assess whether in patients with intramural VAs and with multiple early activation sites (EASs), sequential ablation of all the early EASs could improve acute and long-term clinical outcomes., Methods: A total of 116 patients undergoing catheter ablation for symptomatic LVOT VAs were enrolled in this study. Thirty-nine patients (34%) were referred for a redo procedure, whereas the remaining presented for a first procedure. Mapping was performed manually in 86 cases (74%) and with a magnetic robotic system (Niobe, Stereotaxis, St. Louis, MO) in the remainder of the cases., Results: Of the 116 patients, 15 (13%) were found to have multiple sites of equally early activation. In patients with multiple EASs, the mean pre-QRS activation time was significantly less than in patients with a single EASs (-26 ± 3 ms vs -38 ± 6 ms; P < .005). Sequential ablation of all the EASs was possible in 14 patients (93%), resulting in complete arrhythmia suppression. After a mean follow-up of 21 ± 5 months, all patients with successful ablation of all multiple early EASs remained free from clinical VAs., Conclusion: Intramural LVOT VAs manifesting with multiple EASs require ablation at all sites to achieve acute and long-term success, particularly if none of the EASs is > -30ms pre-QRS activation time., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Mortality caused by ventricular arrhythmias (VAs) remains a problem of epidemic proportions. Understanding current trends on admission of VA, patient characteristics, morbidity, mortality, and health care utilization could help us improve allocation of health care resources and risk prediction., Objective: The purpose of this study was to investigate clinical outcomes of VA, including ventricular tachycardia (VT), implantable cardioverter-defibrillator (ICD) shocks, and sudden cardiac death (SCD); and to identify predictors of morbidity and mortality, patterns of utilization of ICD and VT ablation, and the impact of such metrics on overall health care utilization., Methods: From 2010-2015, we identified 290,998 VA hospitalizations, which were stratified into group 1: normal heart; group 2: ischemic heart disease (IHD); group 3: nonischemic heart disease (non-IHD); group 4: ICD shocks; and group 5: SCD (cardiac arrest without ICD shock)., Results: The number of admissions for VA decreased during the study period (except for patients with SCD and ICD shock, which increased); in-hospital mortality in patients admitted with VA and SCD increased; utilization of VT ablation in patients with ICD shocks and IHD increased; ICD implantation decreased in non-IHD patients and IHD patients; and admission for SCD was the strongest predictor of in-hospital mortality, followed by patients with non-IHD, patients with ICD shocks, and all patients with a Charlson comorbidity index ≥2., Conclusion: We report a decrease in admissions for VA, decreased ICD utilization, a change in pattern of VT ablation utilization, and an increase of in-hospital mortality in SCD patients. Predictors of adverse outcomes identified in our study should be considered when developing risk models for patients undergoing risk assessment for SCD., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Spontaneous echocardiographic contrast ("smoke") within the left atrial cavity on transesophageal echocardiography (TEE) suggests low blood flow velocities in the heart that may lead to thromboembolic (TE) events., Objective: The purpose of this study was to evaluate the risk of TE events in the periprocedural period and at long-term follow-up in atrial fibrillation (AF) patients having dense smoke on preprocedural TEE., Methods: A total of 2511 patients undergoing AF ablation were included in this analysis. They were classified as group 1 (dense smoke detected on TEE at baseline; n = 234) and group 2 (no smoke on baseline TEE; n = 2277). Patients were followed up for TE events, which included both stroke and transient ischemic attacks (TIAs). In order to attenuate the observed imbalance in baseline covariates between the study groups, a propensity score matching technique was used (covariates were age, sex, AF type, diabetes, and CHADS 2 VASc score)., Results: In the periprocedural period, no TE events were reported in group 1 and 3 events (0.13%) were reported in group 2. At follow-up of 6.62 ± 2.01 years, 6 (2.6%) TE complications (2 TIA, 4 stroke) occurred in group 1 and 16 (0.70%) TE complications (6 TIA, 10 stroke) in group 2 (P = .004). In the propensity-matched population, 6 (2.56%) TE complications occurred in group 1 and 1 (0.2%) in group 2 (P = .007)., Conclusion: In our study population, the presence of dense left atrial smoke did not show any correlation with periprocedural TE events in patients undergoing catheter ablation with uninterrupted anticoagulation. However, significant association was observed with late stroke/TIA, irrespective of CHA 2 DS 2 -VASc score., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Esophageal thermal injury is a feared complication of radiofrequency ablation for atrial fibrillation (AF). Rise in luminal esophageal temperature (LET) limits the ability to deliver radiofrequency energy on the posterior wall of the left atrium., Objective: The purpose of this study was to evaluate the feasibility, safety, and efficacy of a mechanical esophageal deviation (ED) tool during AF ablation., Methods: We evaluated 687 patients who underwent radiofrequency ablation for AF. In 209 patients, the EsoSure (Northeast Scientific) was used to deflect the esophagus away from the ablation site. Propensity score matching was performed to obtain 180 patients each in the ED and non-ED arms. ED was used for LET rise seen in 61.7% of patients (111/180) and was used if the esophagus was in the line of ablation on fluoroscopy in 38.3% of patients (69/180)., Results: Mean deviation of trailing edge of esophagus with EsoSure was 2.45 ± 0.9 cm (range 1-4.5). LET rise >1°C was significantly lower in the ED than non-ED group (3% vs 79.4%; P <.001). Mean LET rise was also lower in the ED arm (ED 0.34 ± 0.59 vs non-ED 1.66 ± 0.54; P <.001). Intraprocedural success of pulmonary vein antral isolation, was slightly improved in the ED arm than in the non-ED arm without statistical significance. AF recurrence was lower in the ED arm at 3-month, 6-month, and 1-year follow-up than in the non-ED arm. No ED-related complications were noted., Conclusion: Mechanical displacement of the esophagus with EsoSure seems to be feasible, safe, and efficacious in enabling adequate radiofrequency energy delivery to the posterior wall of the left atrium without significant LET rise and obvious clinical signs of esophageal injury., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Pulmonary vein isolation (PVI) in conjunction with isolation of the posterior left atrial wall (PVI+PWI) is associated with improved clinical outcomes in certain patients with atrial fibrillation (AF)., Objective: The purpose of this multicenter study was to evaluate the acute and long-term outcomes of PVI+PWI vs PVI alone performed using cryoballoon ablation in patients with persistent AF (persAF)., Methods: We examined the procedural safety and efficacy and short- and long-term outcomes in 390 consecutive patients with persAF who underwent a first-time cryoballoon ablation procedure using PVI+PWI (n = 222 [56.9%]) vs PVI alone (n = 168 [43.1%])., Results: Acute isolation was achieved in 99.7% of all pulmonary veins (PVI+PWI = 99.8% vs PVI alone = 99.3%; P = .23) using 6.3 ± 1.4 applications and 17 ± 2 minutes of cryoablation. PWI was achieved using 13.7 ± 3.2 applications and 34 ± 10 minutes of cryoablation. Adjunct radiofrequency ablation was required in 1.8% of patients to complete PVI (4 ± 2 minutes) and in 32.4% to complete PWI (5 ± 2 minutes). PVI+PWI yielded significantly greater posterior wall (77.2% ± 6.4% vs 40.6% ± 4.9%; P < .001) and total left atrial (53.3% ± 4.2% vs 36.3% ± 3.8%; P < .001) isolation. In addition, PVI+PWI was associated with greater AF termination (19.8% vs 8.9%; P = .003) and conversion to atrial flutters (12.2% vs 5.4%; P = .02). Adverse events were similar in both groups, whereas recurrence of AF and all atrial arrhythmias was lower with PVI+PWI at 12 months of follow-up. Moreover, in a Cox regression analysis, PVI+PWI emerged as a significant predictor of freedom from recurrent atrial arrhythmias (hazard ratio: 2.04; 95% confidence interval: 1.15-3.61; P = .015)., Conclusion: PVI+PWI can be achieved safely and effectively using the cryoballoon. This approach appears superior to PVI alone in patients with persAF., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to evaluate the characteristics and outcome of patients undergoing ablation after electrical storm (ES)., Methods: Clinical and procedural characteristics, ventricular tachycardia (VT) recurrence, and mortality rates from 1940 patients undergoing VT ablation were compared between patients with and without ES., Results: The group of 677 patients with ES (34.9%) were older, were more frequently men, and had a lower ejection fraction, more advanced heart failure, and a higher prevalence of cardiovascular comorbidities as compared with those without ES (86.1% patients with ES had ≥2 comorbidities vs 71.4%; P < .001). Patients with ES had more inducible VTs (2.5 ± 1.8 vs 1.9 ± 1.9; P < .001), required longer procedures (296.1 ± 119.1 minutes vs 265.7 ± 110.3 minutes; P < .001), and had a higher in-hospital mortality (42 deaths [6.2%] vs 18 deaths [1.4%]; P < .001). At 1-year follow-up, patients with ES experienced a higher risk of VT recurrence and mortality (32.1% vs 22.6% and 20.1% vs 8.5%; long-rank, P < .001 for both). Among patients with ES, those without any inducible VT after ablation had a higher survival rate (86.3%) than did those with nonclinical VTs only (72.9%), those with clinical VTs inducible at programmed electrical stimulation (51.2%), and not-tested patients (65.0%) (long-rank, P < .001 for all). In multivariate analysis, ES remained an independent predictor of in-hospital mortality, VT recurrence, and 1-year mortality (P < .001)., Conclusion: Patients with ES have a high risk of VT recurrence and mortality. Patient and procedure characteristics are consistent with advanced cardiac disease and longer and more complex procedures. In patients with ES, acute procedural success is associated with a significant reduction in VT recurrence and improved 1-year survival., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Epicardial ablation is often necessary for the treatment of complex arrhythmias refractory to endocardial ablation. Conventional needle access to the pericardial space is considered quite challenging, and it is often associated with several potential complications, particularly inadvertent right ventricular puncture. The novel EpiAccess needle tip is embedded with a pressure sensor able to report the pressure waveform in real time when used with the EpiAccess System., Objective: We prospectively evaluated the feasibility and safety of the EpiAccess System by EpiEP, Inc., with a novel epicardial access needle in a multicenter study., Methods: Twenty-five patients with a clinical need for epicardial access were enrolled. The EpiAccess needle and EpiAccess System were used for epicardial access in each case. Successful epicardial access, defined as the ability to introduce a guidewire into the epicardial space, was assessed via the device and confirmed with fluoroscopy. Significant pericardial bleeding was defined as >80 mL of blood by using peer review article definitions., Results: Patients were men (76%) with a mean age of 62 years (range 28-84 years). Epicardial access for ventricular tachycardia ablation was indicated in 80% of the patients. Successful epicardial access was obtained in all cases, with pressure monitoring guiding pericardial wire access in all cases. One delayed pericardial effusion occurred., Conclusion: Epicardial access with the novel EpiAccess needle and System with real-time pressure monitoring is feasible and safe. The pressure monitoring capability identifies successfully the epicardial space, facilitating access and potentially minimizing complications. This has relevant clinical implications., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Data evaluating repeat radiofrequency ablation (>1RFA) of ventricular tachycardia (VT) are limited., Objective: The purpose of this study was to determine the safety and outcomes of VT >1RFA in patients with structural heart disease., Methods: Patients with structural heart disease undergoing VT RFA at 12 centers with data on prior RFA history were included. Characteristics and outcomes were compared between first-time (1RFA) and >1RFA patients., Results: Of 1990 patients, 740 had >1RFA (mean 1.4 ± 0.9, range 1-10). >1RFA vs 1RFA patients did not differ with regard to age (62 ± 13 years vs 62 ± 13 years), left ventricular ejection fraction (33% ± 13% vs 34% ± 13%), or sex (88% vs 87% men), but they more often were nonischemic (53% vs 41%), had implantable cardioverter-defibrillator shocks (70% vs 63%) or VT storm (38% vs 33%), and had been treated with amiodarone (55% vs 48%) or ≥2 antiarrhythmic drugs (22% vs 14%). >1RFA procedures were longer (300 ± 122 minutes vs 266 ± 110 minutes), involved more epicardial access (41% vs 21%), induced VTs (2.4 ± 2.2 vs 1.9 ± 1.6) and only unmappable VTs (15% vs 9%), and VT was more often inducible after RFA (42% vs 33%, all P <.03). Total complications were higher for >1RFA vs 1RFA (8% vs 5%, P <.01), mostly related to pericardial effusion (2.4% vs 1.3%, P = .07) and venous thrombosis (0.8% vs 0.2%, P = .06). VT recurrence was higher for >1RFA vs 1RFA (29% vs 24%, P <.001). Survival was worse for >1RFA vs 1RFA if VT recurred (67% vs 78%, P = .003) but was equivalent if successful (93% vs 92%, P = .96)., Conclusion: Patients requiring repeat VT ablation differ significantly from those undergoing first-time ablation. Despite more challenging ablation characteristics, VT-free survival after repeat ablations is encouraging. Mortality is comparable if VT does not recur after RFA at specialized centers., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: In the stroke prevention trials of left atrial appendage closure with the Watchman device (Boston Scientific), a postimplantation antithrombotic regimen of 6 weeks of warfarin was used., Objective: Given the clinical complexity of warfarin use, the purpose of this study was to study the relative feasibility and safety of using non-warfarin oral anticoagulants (NOACs) instead of warfarin during the peri- and initial postimplantation periods after Watchman implantation., Methods: This was a retrospective multicenter study of consecutive patients undergoing Watchman implantation and receiving peri- and postprocedural NOACs or warfarin. Transesophageal echocardiography or chest computed tomography was performed between 6 weeks and 4 months postimplant to assess for device-related thrombosis. Bleeding and thromboembolic events also were evaluated at the time of follow-up., Results: In 5 centers, 214 patients received NOACs (46% apixaban, 46% rivaroxaban, 7% dabigatran, and 1% edoxaban) in either an uninterrupted (82%) or a single-held-dose (16%) fashion. Compared to a control group receiving uninterrupted warfarin (n = 212), the rates of periprocedural complications, including bleeding events, were similar (2.8% vs 2.4%, P = 1). At follow-up, the rates of device-related thrombosis (0.9% vs 0.5%, P = 1), composite of thromboembolism or device-related thrombosis (1.4% vs 0.9%, P = 1), and postprocedure bleeding events (0.5% vs 0.9%, P = .6) also were comparable between the NOAC and warfarin groups., Conclusion: NOACs proved to be a feasible peri- and postprocedural alternative regimen to warfarin for preventing device-related thrombosis and thromboembolic complications expected early after appendage closure with the Watchman device, without increasing the risk of bleeding., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)