Background: The Subcutaneous ICD (S-ICD) is safe and effective for sudden cardiac death prevention. However, patients in previous S-ICD studies had fewer comorbidities, less left ventricular dysfunction and received more inappropriate shocks (IAS) than in typical transvenous (TV)-ICD trials. The UNTOUCHED trial was designed to evaluate the IAS rate in a more typical, contemporary ICD patient population implanted with the S-ICD using standardized programming and enhanced discrimination algorithms. Methods: Primary prevention patients with left ventricular ejection fraction (LVEF) ≤ 35% and no pacing indications were included. Generation 2 or 3 S-ICD devices were implanted and programmed with rate-based therapy delivery for rates ≥ 250 beats per minute (bpm) and morphology discrimination for rates ≥200 and < 250 bpm. Patients were followed for 18 months. The primary endpoint was the IAS free rate compared to a 91.6% performance goal, derived from the results for the ICD-only patients in the MADIT-RIT study. Kaplan-Meier analyses were performed to evaluate event-free rates for IAS, all cause shock, and complications. Multivariable proportional hazard analysis was performed to determine predictors of endpoints. Results: S-ICD implant was attempted in 1116 patients and 1111 patients were included in post-implant follow-up analysis. The cohort had a mean age of 55.8±12.4 years, 25.6% women, 23.4% black race, 53.5% with ischemic heart disease, 87.7% with symptomatic heart failure and a mean LVEF of 26.4±5.8%. Eighteen-month freedom from IAS was 95.9% (Lower confidence limit LCL 94.8%). Predictors of reduced incidence of IAS were implanting the most recent generation of device, using the three-incision technique, no history of atrial fibrillation, and ischemic etiology. The 18-month all cause shock free rate was 90.6% (LCL 89.0%), meeting the prespecified performance goal of 85.8%. Conversion success rate for appropriate, discrete episodes was 98.4%. Complication free rate at 18 months was 92.7%. Conclusions: This study demonstrates high efficacy and safety with contemporary S-ICD devices and programming despite the relatively high incidence of co-morbidities in comparison to earlier S-ICD trials. The inappropriate shock rate (3.1% at one year) is the lowest reported for the S-ICD and lower than many TV ICD studies using contemporary programming to reduce IAS. Clinical Trial Registration: URL https://clinicaltrials.gov Unique Identifier NCT02433379

A new algorithm that uses correlation of the existing complex to previous complexes reduced TWOS episodes by approximately 40%. The algorithm has potential for a clinically meaningful decrease in inappropriate shocks.

BACKGROUND The subcutaneous implantable cardioverterdefibrillator (S-ICD) has shown favorable outcomes in large registries with broad inclusion criteria. The cohorts reported had less heart disease and fewer comorbidities than standard ICD populations.OBJECTIVE The purpose of this study is to characterize acute performance for primary prevention patients with a left ventricular ejection fraction (LVEF) 35% (primary prevention 35%).METHODS Primary prevention 35% patients with no prior documented sustained ventricular tachycardia (VT), pacing indication, end-stage heart failure, or advanced renal failure were prospectively enrolled. Analyses included descriptive statistics, Kaplan-Meier time to event, and multivariable linear and logistic regression. RESULTSIn 1112 of 1116 patients, an S-ICD was successfully implanted (99.6%). Predictors for longer procedure time included 3-incision technique, higher body mass index (BMI), performing defibrillation testing (DFT), imaging, younger age, black race, and European vs North American centers. Patients undergoing DFT (82%) were successfully converted (99.2%; 93.5% converting at 65 J). Higher BMI was predictive of failing DFT at 65 J. The rate of 30-day freedom Disclosures: Drs Lambiase, Dinerman, and Barr report no disclosures. Dr Boersma serves as a consultant and receives research grants from Boston Scientific and Medtronic. Dr El-Chami receives honoraria for Boston Scientific and Medtronic. Dr Bongiorni receives honoraria from Abbott Medical Italia S.p.a., Biotronik, Boston Scientific, and Medtronic. Dr Burke is a consultant and receives honoraria from Boston Scientific; receives research grants from Boston Scientific; and has equity in AtaCor Medical. Dr Knops reports honoraria for consulting and speaking, and research grants from Boston Scientific. Dr Aasbo reports Boston Scientific and Biotronik consulting fees. Dr Deharo receives research grants, travel grants, and honoraria for lectures/consulting from Medtronic, Boston Scientific, Abbott, Microport, and Biotronik. Dr Russo reports research grants from Boston Scientific, serves on steering Committees for Boston Scientific and Apple, and receives royalties from Up-to-Date. Dr Shaik receives honoraria for consulting, research, and speaking from Boston Scientific, Abbott, Biotronik, and Biosense Webster. Ms Appl, Mr Carter, Dr Brisben, and Dr Stein are all employees and shareholders of Boston Scientific. Dr Gold receives honoraria and research grants from Boston Scientific and Medtronic. Funding: The UNTOUCHED study was funded entirely by Boston Scientific Corporation.

Aims To report 5-year outcomes of EFFORTLESS registry patients with early generation subcutaneous implantable cardioverter-defibrillator (S-ICD) devices. Methods and results Kaplan–Meier, trend and multivariable analyses were performed for mortality and late (years 2–5) complications, appropriate shock (AS) and inappropriate shock (IAS) rates. Nine hundred and eighty-four of 994 enrolled patients with diverse diagnoses (28% female, 48 ± 17 years, body mass index 27 ± 6 kg/m2, ejection fraction 43 ± 18%) underwent S-ICD implantation. Median follow-up was 5.1 years (interquartile range 4.7–5.5 years). All-cause mortality was 9.3% (95% confidence interval 7.2–11.3%) at 5 years; 703 patients remained in follow-up on study completion, 171 withdrew including 87 (8.8%) with device explanted, and 65 (6.6%) lost to follow-up. Of the explants, only 20 (2.0%) patients needed a transvenous device for pacing indications. First and final shock efficacy for discrete ventricular arrhythmias was consistent at 90% and 98%, respectively, with storm episode final shock efficacy at 95.2%. Time to therapy remained unaltered. Overall 1- and 5-year complication rates were 8.9% and 15.2%, respectively. Early complications did not predict later complications. There were no structural lead failures. Inappropriate shock rates at 1 and 5 years were 8.7% and 16.9%, respectively. Self-terminating inappropriately sensed episodes predicted late IAS. Predictors of late AS included self-terminating appropriately sensed episodes and earlier AS. Conclusion In this diverse S-ICD registry population, spontaneous shock efficacy was consistently high over 5 years. Very few patients underwent S-ICD replacement with a transvenous device for pacing indications. Treated and self-terminating arrhythmic episodes predict future shock events, which should encourage more personalized device optimization. Key question Is subcutaneous implantable cardioverter-defibrillator (S-ICD) shock efficacy maintained over time? Key finding Subcutaneous implantable cardioverter-defibrillator shock efficacy remains high for discrete and storm episodes. For discrete episodes first and final shock efficacy do not change over time or by rhythm type. Take-home message The EFFORTLESS study 5-year results provide the longest follow up of a large patient cohort implanted with the S-ICD. For 984 patients with a median follow-up of 5.1 years, the S-ICD maintains a high level of shock efficacy of 98%.