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Background: Limited data on the real-world safety and efficacy of leadless pacemakers (LPMs) post-transvenous lead extraction (TLE) are available., Objective: The purpose of this study was to assess the long-term safety and effectiveness of LPMs following TLE in comparison with LPMs de novo implantation., Methods: Consecutive patients who underwent LPM implantation in 12 European centers joining the International LEAdless PacemakEr Registry were enrolled. The primary end point was the comparison of LPM-related complication rate at implantation and during follow-up (FU) between groups. Differences in electrical performance were deemed secondary outcomes., Results: Of the 1179 patients enrolled, 15.6% underwent a previous TLE. During a median FU of 33 (interquartile range 24-47) months, LPM-related major complications and all-cause mortality did not differ between groups (TLE group: 1.6% and 5.4% vs de novo group: 2.2% and 7.8%; P = .785 and P = .288, respectively). Pacing threshold (PT) was higher in the TLE group at implantation and during FU, with very high PT (>2 V@0.24 ms) patients being more represented than in the de novo implantation group (5.4% vs 1.6 %; P = .004). When the LPM was deployed at a different right ventricular (RV) location than the one where the previous transvenous RV lead was extracted, a lower proportion of high PT (>1-2 V@0.24 ms) patients at implantation, 1-month FU, and 12-month FU (5.9% vs 18.2%, P = .012; 3.4% vs 12.9%, P = .026; and 4.3% vs 14.5%, P = .037, respectively) was found., Conclusion: LPMs showed a satisfactory safety and efficacy profile after TLE. Better electrical parameters were obtained when LPMs were implanted at a different RV location than the one where the previous transvenous RV lead was extracted., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Elevated resting heart rate is a risk factor for cardiovascular events., Objective: The purpose of this study was to investigate the clinical significance of nocturnal heart rate (nHR) and 24-hour mean heart rate (24h-HR) obtained by continuous remote monitoring (RM) of implantable devices., Methods: We analyzed daily-sampled trends of nHR, 24h-HR, and physical activity in patients on β-blocker therapy for chronic heart failure and with implantable cardioverter-defibrillators or cardiac resynchronization therapy defibrillators (CRT-Ds). Patients were grouped by average nHR and 24h-HR quartile during follow-up to estimate the respective incidence of nonarrhythmic death and device-treated ventricular tachycardia/fibrillation (VT/VF)., Results: The study cohort included 1330 patients (median age 69 years [interquartile range 61-77 years]; 41% [n = 550] with CRT-D; median follow-up 25 months [interquartile range 13-42 months]). Compared with patients in the lowest nHR quartile (≤57 beats/min) group, patients in the highest quartile group (>65 beats/min) had an increased risk of nonarrhythmic death (adjusted hazard ratio [AHR] 2.25; 95% confidence interval [CI] 1.13-4.50; P = .021) and VT/VF (AHR 1.98; 95% CI 1.40-2.79; P < .001) and were characterized by the lowest level of physical activity (P ≤ .0004 vs every other nHR quartiles). The highest 24h-HR quartile group (>75 beats/min) showed an increased risk of VT/VF (AHR 2.13; 95% CI 1.52-2.99; P < .001) and a weaker though significant association with nonarrhythmic mortality (AHR 1.80; 95% CI 1.00-3.22; P = .05) as compared with the lowest 24h-HR quartile group (≤65 beats/min)., Conclusion: In remotely monitored patients with implantable cardioverter-defibrillator/CRT-D on β-blocker therapy for heart failure, elevated heart rates (nHR >65 beats/min and 24h-HR >75 beats/min) were associated with increased mortality and VT/VF risk. nHR showed a stronger association than 24h-HR with worst prognosis and lowest physical activity., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: In heart failure (HF) patients, atrial fibrillation (AF) is associated with a worse prognosis. Implantable cardioverter-defibrillator (ICD) diagnostics allow continuous monitoring of AF and are equipped with algorithms for HF monitoring., Objective: We evaluated the association between the values of the multisensor HF HeartLogic index and the incidence of AF, and assessed the performance of the index in detecting follow-up periods of significantly increased AF risk., Methods: The HeartLogic feature was activated in 568 ICD patients. Median follow-up was 25 months [25th-75th percentile (15-35)]. The HeartLogic algorithm calculates a daily HF index and identifies periods of IN-alert state on the basis of a configurable threshold. The endpoints were daily AF burden ≥5 minutes, ≥6 hours, and ≥23 hours., Results: The HeartLogic index crossed the threshold value 1200 times. AF burden ≥5 minutes/day was documented in 183 patients (32%), ≥6 hours/day in 118 patients (21%), and ≥23 hours/day in 89 patients (16%). The weekly time of IN-alert state was independently associated with AF burden ≥5 minutes/day (hazard ratio [HR] 1.95; 95% confidence interval [CI] 1.22-3.13; P = .005), ≥6 hours/day (HR 2.66; 95% CI 1.60-4.44; P <.001), and ≥23 hours/day (HR 3.32; 95% CI 1.83-6.02; P <.001), after correction for baseline confounders. Comparison of the episode rates in the IN-alert state with those in the OUT-of-alert state yielded HR ranging from 1.57 to 3.11 for AF burden from ≥5 minutes to ≥23 hours., Conclusions: The HeartLogic alert state was independently associated with AF occurrence. The intervals of time defined by the algorithm as periods of increased risk of HF allow risk stratification of AF according to various thresholds of daily burden., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Few studies have examined the causes of syncope/collapse recurrences in patients with a previously implanted pacemaker for bradyarrhythmic syncope., Objective: The purpose of this study was to assess the causes of syncope/collapse recurrences after pacemaker implantation for bradyarrhythmic syncope in a large patient population., Methods: The SYNCOpal recurrences in patients treated with permanent PACing for bradyarrhythmic syncope (SYNCOPACED) registry was a prospective multicenter observational registry enrolling 1364 consecutive patients undergoing pacemaker implantation for bradyarrhythmic syncope. During follow-up, the time to the first syncope/collapse recurrence was recorded. Patients with syncope/collapse recurrences underwent a predefined diagnostic workup aimed at establishing the mechanism of syncope/collapse., Results: During a median follow-up of 50 months, 213 patients (15.6%) reported at least 1 syncope/collapse recurrence. The risk of syncope/collapse recurrence was highest in patients who underwent implantation for cardioinhibitory vasovagal syncope (26.4%), followed by unexplained syncope and chronic bifascicular block (21.5%), cardioinhibitory carotid sinus syndrome (17.2%), atrial fibrillation needing pacing (15.5%), atrioventricular block (13.6%), and sinus node disease (12.5%) (P = .017). The most frequent cause of syncope/collapse recurrence was reflex syncope (27.7%), followed by orthostatic hypotension (26.3%), pacemaker or lead malfunction (5.6%), structural cardiac disease (5.2%), and atrial and ventricular tachyarrhythmias (4.7% and 3.8%, respectively). In 26.8% of cases, the mechanism of syncope/collapse remained unexplained., Conclusion: In patients receiving a pacemaker for bradyarrhythmic syncope, reflex syncope and orthostatic hypotension are the most frequent mechanisms of syncope/collapse recurrence after implantation. Pacing system malfunction, structural cardiac diseases, and tachyarrhythmias are rare mechanisms. The mechanism remains unexplained in >25% of patients., (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: The subcutaneous implantable cardioverter-defibrillator (S-ICD) does not require the insertion of any leads into the cardiovascular system., Objective: The aims of the study were to describe current practice and to measure outcomes associated with S-ICD or standard single-chamber transvenous ICD (TV-ICD) use after TV-ICD explantation., Methods: We analyzed all consecutive patients who underwent transvenous extraction of an ICD and subsequent implantation of an S-ICD or a single-chamber TV-ICD at 12 Italian centers from 2011 to 2017., Results: A total of 229 patients were extracted and subsequently reimplanted with an S-ICD (90; 39%) or a single-chamber TV-ICD (139; 61%). S-ICD implantation increased from 9% in 2011 to 85% in 2017 (P < .001). Patients reimplanted with an S-ICD were younger (53 ± 13 years vs 60 ± 18 years; P = .011) and more frequently had undergone extraction owing to infection (73% vs 52%; P < .001). The rates of complications at follow-up were comparable between groups (hazard ratio 0.97; 95% confidence interval 0.49-1.92; P = .940). No lead failures, systemic infections, or system-related deaths occurred in the S-ICD group. In the TV-ICD group, 1 lead fracture occurred and 2 systemic infections were reported, resulting in death in 1 case. In the S-ICD group, the rate of complications was lower when the generator was positioned in a sub- or intermuscular pocket (hazard ratio 0.21; 95% confidence interval 0.05-0.87; P = .048)., Conclusion: Our results show an increasing use of S-ICD over the years in patients undergoing TV-ICD explantation. An S-ICD is preferably adopted in young patients, mostly in the case of infection. The complication rate was comparable between groups and decreased when a sub- or intermuscular S-ICD generator position was adopted., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)