title: Evaluation of subcutaneous ICD early performance in hypertrophic cardiomyopathy from the pooled EFFORTLESS and IDE cohorts.
abstract: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a potential alternative to transvenous systems in hypertrophic cardiomyopathy (HCM) where lead complications are a significant issue.
  
  
  
  To compare the S-ICD efficacy of defibrillation threshold (DFT) testing, arrhythmia therapy, and complications in HCM versus non-HCM patients.
  
  
  
  Outcomes of patients with HCM implanted with S-ICD were compared to non-HCM S-ICD recipients using pooled data from a total of 872 subjects enrolled in the EFFORTLESS Registry and US IDE study.
  
  
  
  The cohort included 99 HCM (75% male) and 773 non-HCM (72% male) patients with a median follow-up of 637 days. The HCM cohort was younger and more likely to receive a primary-prevention S-ICD (88.5% vs 67.5%, P < .0001). During implant testing, successful defibrillation at ≤80 J was achieved in 98.9% of HCM and 98.5% of non-HCM patients. One year postoperative complication-free rates were similar: 92.7% in HCM (with no lead complications) versus 89.5% in non-HCM. There were 3 appropriate shocks for ventricular tachycardia in 3 HCM patients that were all converted by the first shock. Overall final shock conversion efficacy was 100% in HCM versus 98% in non-HCM (P = ns). Inappropriate shocks occurred in 12.5% of HCM patients and 10.3% of non-HCM patients (P = ns), being reduced by 47% using dual-zone programming.
  
  
  
  These initial data indicate the S-ICD is safe and effective in patients with HCM who are at high risk of ventricular arrhythmias and pass preimplantation electrocardiogram screening. Inappropriate shocks were mainly due to T-wave oversensing, but there were no lead complications requiring reintervention.
authors.affiliation: Barts Heart Centre & UCL, London, UK. Electronic address: d.lambiase@ucl.ac.uk.
authors.forename: Pier D
authors.initials: PD
authors.lastname: Lambiase
authors.affiliation: Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Gold
authors.affiliation: Auckland City Hospital, Auckland, New Zealand.
authors.forename: Margaret
authors.initials: M
authors.lastname: Hood
authors.affiliation: St Antonius Ziekenhuis, Nieuwegein, Netherlands.
authors.forename: Lucas
authors.initials: L
authors.lastname: Boersma
authors.affiliation: Erasmus Medical Center, Rotterdam, Netherlands.
authors.forename: Dominic A M J
authors.initials: DAMJ
authors.lastname: Theuns
authors.affiliation: Heart Rhythm Center, University of Chicago, Chicago, Illinois.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Burke
authors.affiliation: Ohio State University, Columbus, Ohio.
authors.forename: Raul
authors.initials: R
authors.lastname: Weiss
authors.affiliation: Cooper University Hospital, Camden, New Jersey.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Russo
authors.affiliation: Grosshadern, University of Munich, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kääb
authors.affiliation: Northwestern University, Chicago, Illinois.
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Knight
mesh_terms: D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications*; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D019544:Equipment Failure Analysis / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D011322:Primary Prevention / Q000379:methods; D012042:Registries; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D016896:Treatment Outcome
keywords: Hypertrophic cardiomyopathy; Subcutaneous ICD; Ventricular arrhythmias