Contemporary Implantable Cardioverter-Defibrillator Benefit: Time to First Therapy in a Large, Real-World Cohort

Background: Implantable cardioverter-defibrillators (ICDs) reduce mortality in patients at risk of sudden cardiac death. Recent improvements in heart failure care may impact the rate of ICD therapy received by patients. Thus, an updated examination of ICD benefit is needed. Objectives: This study sought to assess time to first therapy in contemporary ICD patients and infer the proportion of appropriate therapies based on an adjudicated subset of randomly selected episodes. Methods: A query of the Medtronic CareLink de-identified database from 2013 to 2024 was performed. First-time Medtronic ICD recipients implanted with a single- or dual-chamber ICD were included. Cumulative incidence function curves were generated for time to first shock therapy, antitachycardia pacing (ATP) therapy, and any therapy (shock or ATP). Three adjudicators analyzed 595 randomly selected episodes manually to assess appropriateness of therapy. Results from adjudication were then used to model therapy appropriateness of the rest of the episodes in the database. Results: There were 237,627 patients (71.8% male) included in the analysis. The cumulative incidence of first appropriate shock, ATP, or any appropriate therapy was 33%, 42%, and 48% at 10 years, respectively. Secondary prevention ICD-indicated patients had a higher 10-year cumulative incidence of first appropriate shock (41% vs 32%), ATP (51% vs 40%), or any appropriate therapy (58% vs 45%) than primary prevention patients. Conclusions: Nearly half of contemporary patients receive appropriate ICD therapy by 10 years postimplantation. These data indicate continued benefit of ICD therapy despite modern refinements to device management and medical and interventional cardiac care.