Evaluation of subcutaneous ICD early performance in hypertrophic cardiomyopathy from the pooled EFFORTLESS and IDE cohorts

• Published in: Heart rhythm Vol. 13; no. 5; pp. 1066 - 1074
• Main Authors: Lambiase, Pier D., Gold, Michael R., Hood, Margaret, Boersma, Lucas, Theuns, Dominic A.M.J., Burke, Martin C., Weiss, Raul, Russo, Andrea M., Kääb, Stefan, Knight, Bradley P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2016
• Subjects: Adult; Aged; Cardiomyopathy, Hypertrophic - complications; Cardiovascular; Death, Sudden, Cardiac - etiology; Death, Sudden, Cardiac - prevention & control; Defibrillators, Implantable - adverse effects; Electric Countershock - adverse effects; Electric Countershock - instrumentation; Electric Countershock - methods; Electrocardiography - methods; Equipment Failure Analysis - statistics & numerical data; Female; Humans; Hypertrophic cardiomyopathy; Male; Middle Aged; Postoperative Complications - diagnosis; Postoperative Complications - epidemiology; Postoperative Complications - etiology; Primary Prevention - methods; Registries; Subcutaneous ICD; Tachycardia, Ventricular - diagnosis; Tachycardia, Ventricular - etiology; Tachycardia, Ventricular - prevention & control; Treatment Outcome; Ventricular arrhythmias; Ventricular arrhythmias; Hypertrophic cardiomyopathy; Subcutaneous ICD
• ISSN: 1547-5271; 1556-3871
• DOI: 10.1016/j.hrthm.2016.01.001

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.