Suitability for subcutaneous defibrillator implantation: results based on data from routine clinical practice

Objective To assess the proportion of current implantable cardioverter defibrillator (ICD) recipients who would be suitable for a subcutaneous lead ICD (S-ICD). Design A retrospective cohort study. Setting Tertiary care facility in the Netherlands. Patients All patients who received a single-or dual-chamber ICD in the Leiden University Medical Center between 2002 and 2011. Patients with a pre-existent indication for cardiac pacing were excluded. Main outcome measure Suitability for an S-ICD defined as not reaching one of the following endpoints during follow-up: (1) an atrial and/or right ventricular pacing indication, (2) successful antitachycardia pacing without a subsequent shock or (3) an upgrade to a CRT-D device. Results During a median follow-up of 3.4 years (IQR 1.7-5.7 years), 463 patients (34% of the total population of 1345 patients) reached an endpoint. The cumulative incidence of ICD recipients suitable for an initial S-ICD implantation was 55.5% (95% CI 52.0% to 59.0%) after 5 years. Significant predictors for the unsuitability of an S-ICD were: secondary prevention, severe heart failure and prolonged QRS duration. Conclusions After 5 years of follow-up, approximately 55% of the patients would have been suitable for an S-ICD implantation. Several baseline clinical characteristics were demonstrated to be useful in the selection of patients suitable for an S-ICD implantation.