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Abstract Introduction The pivotal study of the extravascular implantable cardioverter‐defibrillator (EV ICD) recently demonstrated primary efficacy and safety endpoints comparable to previous ICD systems. Patient experience with this novel device has not been reported. The current study examined the standardized patient‐reported outcome (PRO) metrics of quality of life (QOL) and patient acceptance of the device. Methods The EV ICD Pivotal Study was a prospective, single‐arm, nonrandomized, global, premarket approval trial. Patients completed the 12‐Item Short Form Survey (SF‐12) QOL surveys at baseline and at 6 months following implant. Additionally, patients completed the Florida Patient Acceptance Survey (FPAS) QOL survey at 6 months. Results From baseline to 6 months, patients within the EV ICD Pivotal Study ( n = 247) reported statistically significant SF‐12 improvements in physical QOL (45.4 ± 9.4 vs. 46.8 ± 9.1 respectively, p = .020) and no changes in mental QOL (49.3 ± 10.4 vs. 50.5 ± 9.7, p = .061). No differences were noted by sex, atrial fibrillation, or the experience of ICD shock. EV ICD patients reported better total FPAS patient acceptance of their ICD than TV‐ICD or S‐ICD patients using historical norms comparisons (80.4 ± 15.7 vs. 70.2 ± 17.8, p < .0001 for S‐ICD and 73.0 ± 17.4, p = .004 for TV‐ICD). Conclusion The initial PROs for EV ICD patients indicated that patients had improvements in physical QOL from baseline to 6‐month follow‐up and markedly better overall acceptance of their ICD compared to a previous study with S‐ICD and TV‐ICD data. These initial results suggest that the EV ICD is evaluated positively by patients.

Abstract Background Antitachycardia pacing (ATP) found in most implantable cardioverter defibrillators (ICDs) is an important therapy for painless termination of ventricular tachycardias (VT). In ICDs programmed to guideline-recommended detection and therapy settings typical ATP success rates are 50-70%.[1-3] The first closed-loop, automated ATP (AATP) algorithm, introduced in 2021, applies an S1 train derived from the detected VT, followed by an S2 derived initially from a refractory period estimator and then adjusted using analysis of the post-pacing interval if ATP fails. The termination efficacy of AATP in the real-world population is unknown. Purpose To assess the effectiveness AATP in a large real-world population. Methods A database of de-identified ICD transmissions from subjects in the United States, Australia, Canada, and New Zealand was queried for AATP treated episodes. ICDs were randomly sampled, biased toward ICDs with multiple treated VT episodes. For rhythms classified as monomorphic ventricular tachycardia, each AATP pulse train was reviewed for: rhythm at delivery, effect of ATP, and any non-capturing pulses. Acceleration was defined as a post-ATP decrease in MVT cycle length (VTCL) of at least 10% and at least 30ms. Acceleration to polymorphic VT or ventricular fibrillation (PVT/VF) was assessed. Rates of termination and acceleration were calculated for all MVT and dichotomized using a 320ms VTCL cutoff. The method of generalized estimating equations (GEE) was used to correct event rates for multiple episodes from a single patient. Results There were 2281 episodes of MVT in 340 patients; 63% of patients had 2 or more episodes. There were 724 episodes with initial VTCL &lt;320ms and 1557 episodes with VTCL ≥320ms. The rate of termination of MVT by AATP was 78% for all VTCL [95% CI: 74%-81%]. In 300 patients (88%) AATP terminated at least one MVT. For MVT with VTCL ≥320ms the termination rate was 80% [95% CI: 75%-83%] and for VTCL &lt;320ms the termination rate was 75% [95% CI: 69%-80%]. The rate of acceleration was 3.6% [95% CI: 2.7%-4.9%], with a 0.8% rate of acceleration to PVT/VF [95% CI: 0.4%-1.8%]. Acceleration led to shock therapy in 63% of accelerated episodes. All MVT accelerated to PVT/VF either spontaneously terminated (4/14) or were successfully converted by a single shock therapy (10/14). All accelerations that remained MVT were successfully treated by the device with either subsequent ATP (35%) or shock therapy (61%), or spontaneously terminated (4%). Conclusion In this large, real-world cohort analysis, automated ATP’s termination rate exceeded the typical success rate of burst ATP, particularly for MVT &lt;320ms. Acceleration to PVT/VF was low and effective first-shock defibrillation was consistent. Subsequent ATP for accelerated MVT had incremental benefit, leading to successful termination one-third of the time. Additional data are currently being prospectively collected in a separate post-approval study.

Abstract Background Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death in patients at high risk for ventricular arrhythmias, but conventional systems carry a risk of transvenous (TV) lead-related complications. The novel extravascular ICD (EV ICD) may reduce some of these complications, while offering anti-tachycardia pacing (ATP), pause prevention pacing, and a device of similar size and projected battery longevity as a TV ICD, by placing a lead substernally. The EV ICD Pivotal study demonstrated EV ICD safety and performance for termination of ventricular arrythmias at 6 months. Longer-term performance is unknown. Purpose To report the chronic safety and performance of the EV ICD system. Methods The extravascular implantable cardioverter defibrillator (EV ICD) Pivotal study was a prospective, international, single-arm, premarket clinical study. Patients with a class I or IIa indication for a single-chamber ICD per ESC or ACC/AHA/HRS guidelines were enrolled. Freedom from major system- and/or procedure-related complications at 18 mo was evaluated, as well as conversion of arrhythmias by anti-tachycardia pacing (ATP) or shock through all available follow up. Rates of ATP success were evaluated using the generalized estimating equation (GEE) and simple proportions. Results Implantation was attempted in 316 patients: 74.7% male, age 53.8±13.1 years, 82% primary prevention, left ventricular ejection fraction of 38.9%±15.4%, and New York Heart Association Class I (23.4%) or II/III (65.5%). Of 299 implanted patients (average follow up 16.2±7.2 mo), 19 experienced 80 spontaneous, appropriately treated arrhythmic episodes: 37 treated by ATP, 15 by ATP and shock, and 28 by shock alone with a Kaplan-Meier (KM) estimated 6.8% of patients experiencing appropriate therapy by 18 mo (Figure). Of discrete episodes treated with shock, 21/21 (100%) were successfully terminated. ATP was delivered in 12 patients, successfully treating 35/52 episodes (67.3%; GEE adjusted 59.0%). Inappropriate shocks occurred in 35 patients through all follow up, with a rate of 10.2% at 1 year. The KM estimate of freedom from major EV ICD system-or procedure-related complications rate through 18 mo was 91.9% (95% CI: 88.2% to 94.4%). The most common event was lead dislodgment (10 events in 9 patients) identified 0 to 120 days post-implant, predominantly due to anchoring technique. Conclusion The safety and effectiveness of a novel EV ICD system with a substernal lead extends through chronic follow up. Shocks were avoided in nearly half of all spontaneous episodes because of the availability of ATP.Figure

AbstractCardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing‐induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre‐procedure evaluation and preparation, implant procedure management, follow‐up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Despite the global COVID-19 pandemic, during the past 2 years, there have been numerous advances in our understanding of arrhythmia mechanisms and diagnosis and in new therapies. We increased our understanding of risk factors and mechanisms of atrial arrhythmias, the prediction of atrial arrhythmias, response to treatment, and outcomes using machine learning and artificial intelligence. There have been new technologies and techniques for atrial fibrillation ablation, including pulsed field ablation. There have been new randomized trials in atrial fibrillation ablation, giving insight about rhythm control, and long-term outcomes. There have been advances in our understanding of treatment of inherited disorders such as catecholaminergic polymorphic ventricular tachycardia. We have gained new insights into the recurrence of ventricular arrhythmias in the setting of various conditions such as myocarditis and inherited cardiomyopathic disorders. Novel computational approaches may help predict occurrence of ventricular arrhythmias and localize arrhythmias to guide ablation. There are further advances in our understanding of noninvasive radiotherapy. We have increased our understanding of the role of His bundle pacing and left bundle branch area pacing to maintain synchronous ventricular activation. There have also been significant advances in the defibrillators, cardiac resynchronization therapy, remote monitoring, and infection prevention. There have been advances in our understanding of the pathways and mechanisms involved in atrial and ventricular arrhythmogenesis.

There is a growing appreciation for differences in epidemiology, treatment, and outcomes of cardiovascular conditions by sex. Historically, cardiovascular clinical trials have under-represented females, but findings have nonetheless been applied to clinical care in a sex-agnostic manner. Thus, much of the collective knowledge about sex-specific cardiovascular outcomes result from post hoc and secondary analyses. In some cases, these investigations have revealed important sex-based differences with implications for optimizing care for female patients with arrhythmias. This review explores the available evidence related to cardiac arrhythmia care among females, with emphasis on areas in which important sex differences are known or suggested. Considerations related to improving female enrollment in clinical trials as a way to establish more robust clinical evidence for the treatment of females are discussed. Areas of remaining evidence gaps are provided, and recommendations for areas of future research and specific action items are suggested. The overarching goal is to improve appreciation for sex-based differences in cardiac arrhythmia care as 1 component of a comprehensive plan to optimize arrhythmia care for all patients.

AbstractIntroductionA wearable cardioverter defibrillator (WCD) is indicated in appropriate patients to reduce the risk for sudden cardiac death. Challenges for patients wearing a WCD have been frequent false shock alarms primarily due to electrocardiogram noise and wear discomfort. The objective of this study was to test a contemporary WCD designed for reduced false shock alarms and improved comfort.MethodsOne hundred and thirty patients with left ventricular ejection fraction ≤40% and an active implantable cardioverter defibrillator (ICD) were fitted with the ASSURE WCD (Kestra Medical Technologies) and followed for 30 days. WCD detection was enabled and shock alarm markers recorded, but shocks and shock alarms were disabled. All WCD episodes and ICD ventricular tachycardia/ventricular fibrillation (VT/VF) episodes were adjudicated. The primary endpoint was the false‐positive shock alarm rate with a performance goal of 1 every 3.4 days (0.29 per patient‐day).ResultsOf 163 WCD episodes, 4 were VT/VF and 159 non‐VT/VF (121 rhythms with noise, 32 uncertain with noise, 6 atrial flutter without noise). Only three false‐positive shock alarm markers were recorded; one false‐positive shock alarm every 1333 patient‐days (0.00075 per patient‐day, 95% confidence interval: 0.00015–0.00361; p < .001). No ICD recorded VT/VF episodes meeting WCD detection criteria (≥170 bpm for ≥20 s) were missed by the WCD during 3501 patient‐days of use. Median wear was 31.0 days (interquartile range [IQR] 2.0) and median daily use 23.0 h (IQR 1.7). Adverse events were mostly mild: skin irritation (19.4%) and musculoskeletal discomfort (8.5%).ConclusionThe ASSURE WCD demonstrated a low false‐positive shock alarm rate, low patient‐reported discomfort, and no serious adverse events.

AbstractBackgroundTransvenous implantable cardioverter defibrillators (TV ICD) provide life‐saving therapy for millions of patients worldwide. However, they are susceptible to several potential short‐ and long‐ term complications including cardiac perforation and pneumothorax, lead dislodgement, venous obstruction, and infection. The extravascular ICD system's novel design and substernal implant approach avoids the risks associated with TV ICDs while still providing pacing features and similar generator size to TV ICDs.Study DesignThe EV ICD pivotal study is a prospective, multicenter, single‐arm, nonrandomized, premarket clinical study designed to examine the safety and acute efficacy of the system. This study will enroll up to 400 patients with a Class I or IIa indication for implantation of an ICD. Implanted subjects will be followed up to approximately 3.5 years, depending on when the patient is enrolled.ObjectiveThe clinical trial is designed to demonstrate safety and effectiveness of the EV ICD system in human use. The safety endpoint is freedom from major complications, while the efficacy endpoint is defibrillation success. Both endpoints will be assessed against prespecified criteria. Additionally, this study will evaluate antitachycardia pacing performance, electrical performance, extracardiac pacing sensation, asystole pacing, appropriate and inappropriate shocks, as well as a summary of adverse events.ConclusionThe EV ICD pivotal study is designed to provide clear evidence addressing the safety and efficacy performance of the EV ICD System.