Primary Results From the Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction (UNTOUCHED) Trial

• Type of Material: Article
• Authors: Michael R. Gold, Medical University of South Carolina; Pier D. Lambiase, University College of London; Mikhael El Chami, Emory University; Reinoud E. Knops, Amsterdam University Medical Center; Johan D. Aasbo, Baptist Health Lexington; Maria Grazia Bongiorni, Azienda Ospedaliero-Universitaria Pisana; Andrea M. Russo, Rowan University; Jean-Claude Deharo, Centre hospitalier Universitaire La Timone Hospital; Martin C. Burke, CorVita Science Foundation; Jay Dinerman, Heart Center Research, LLC.; Craig S. Barr, Russells Hall Hospital; Naushad Shaik, AdventHealth; Nathan Carter, Boston Scientific Corporation; Thomas Stoltz, Boston Scientific Corporation; Kenneth M. Stein, Boston Scientific Corporation; Amy J. Brisben, Boston Scientific Corporation; Lucas V.A. Boersma, St. Antonius Ziekenhuis
• Language: English
• Date: 2021-01-05
• Publisher: LIPPINCOTT WILLIAMS & WILKINS
• Publication Version: Final Published Version
• Copyright Statement: © 2020 The Authors.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1161/CIRCULATIONAHA.120.048728
• Title of Journal or Parent Work: CIRCULATION
• Volume: 143
• Issue: 1
• Start Page: 7
• End Page: 17
• Grant/Funding Information: The UNTOUCHED study was funded entirely by Boston Scientific Corp.
• Keywords: sudden cardiac death; Peripheral Vascular Disease; ventricular tachycardia; defibrillators, implantable; Cardiac & Cardiovascular Systems; Science & Technology; primary prevention; heart failure; ventricular fibrillation; arrhythmias, cardiac; Cardiovascular System & Cardiology; Life Sciences & Biomedicine
• Research Categories: Engineering, Biomedical

Abstract

Background: The subcutaneous (S) implantable cardioverter-defibrillator (ICD) is safe and effective for sudden cardiac death prevention. However, patients in previous S-ICD studies had fewer comorbidities, had less left ventricular dysfunction, and received more inappropriate shocks (IAS) than in typical transvenous ICD trials. The UNTOUCHED trial (Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction) 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 ≤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 and morphology discrimination for rates ≥200 and <250 beats per minute. Patients were followed for 18 months. The primary end point was the IAS-free rate compared with a 91.6% performance goal, derived from the results for the ICD-only patients in the MADIT-RIT study (Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy). 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 end points. Results: S-ICD implant was attempted in 1116 patients, and 1111 patients were included in postimplant follow-up analysis. The cohort had a mean age of 55.8±12.4 years, 25.6% were women, 23.4% were Black, 53.5% had ischemic heart disease, 87.7% had symptomatic heart failure, and the mean left ventricular ejection fraction was 26.4±5.8%. Eighteen-month freedom from IAS was 95.9% (lower confidence limit, 94.8%). Predictors of reduced incidence of IAS were implanting the most recent generation of device, using the 3-incision technique, no history of atrial fibrillation, and ischemic cause. The 18-month all-cause shock-free rate was 90.6% (lower confidence limit, 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 comorbidities in comparison with earlier S-ICD trials. The inappropriate shock rate (3.1% at 1 year) is the lowest reported for the S-ICD and lower than many transvenous ICD studies using contemporary programming to reduce IAS. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02433379.