Appropriate and inappropriate implantable cardioverter defibrillator therapy rates in a contemporary cohort

Implantable cardioverter-defibrillators (ICDs) are effective in preventing sudden cardiac death; however, contemporary data regarding appropriate and inappropriate device therapy rates from India remains limited.

To evaluate rate of appropriate and inappropriate ICD therapies in a cohort of patients who underwent ICD or CRT-D implantation for either primary or secondary prevention at a tertiary care centre METHODS: We conducted a retrospective single-centre study of 190 patients who underwent ICD or CRT-D implantation between 2010 and 2024 for primary or secondary prevention. The primary outcome included appropriate and inappropriate ICD therapy rates assessed using Kaplan-Meier analysis RESULTS: The mean age of cohort was 53.1 ± 12.5 years. Secondary prevention accounted for 79% of implants. Over mean follow-up of 43.4 ± 39.6 months, appropriate ICD therapy occurred in 23.2% of patients, with median time to first therapy of 28.5 months. The cumulative incidence of appropriate therapy was 6% at 1 year and 22% at 3 years. Inappropriate therapy occurred in 8.9% of patients with cumulative incidence of 4% and 8% at 1 and 3 years respectively. The rates of appropriate and inappropriate therapies were not statistically different between primary and secondary prevention groups (p = 0.92 and 0.72 respectively) and between ischemic and non-ischemic subset (p = 0.56 and 0.32 respectively).

In this contemporary Indian cohort, ICD therapies remain substantial despite advances in GDMT, with a persistent long-term risk of ventricular arrhythmias. These findings support continued guideline-based ICD use and highlight the need to improve ICD utilization, particularly for primary prevention.