Temporal evolution of clinical event risk after primary-prevention ICD implantation: Chagas vs. non-Chagas dilated cardiomyopathy.

Chagas cardiomyopathy evolves through progressive myocardial injury that may alter the temporal distribution of arrhythmic risk compared with other dilated substrates. We analysed a two-centre registry of consecutive primary-prevention implantable cardioverter-defibrillator (ICD) recipients in Buenos Aires (2008-2025), excluding cardiomyopathies in which ICD indication is not based on ventricular dysfunction. The final cohort comprised 194 patients: 50 with Chagas cardiomyopathy (26%), 83 with ischaemic (43%) and 61 with non-ischaemic dilated cardiomyopathy (31%). Median LVEF was 30% in both groups. The primary endpoint was a composite of appropriate ICD therapy, adjudicated on stored electrograms, or all-cause death. Pre-planned analyses included multivariable Cox regression, period-specific models split at 5 years, competing-risk regression and restricted mean survival time (RMST). The endpoint occurred in 109 patients. Cumulative incidence was lower in Chagas patients at 1 year (2.1% vs. 12.2%) and 5 years (19.5% vs. 42.4%), and Chagas patients accumulated 682 additional event-free days at 10-year RMST (95% CI: 258-1047;