Appropriate ICD Therapies in Primary Prevention: A Propensity-Matched Comparison of Contemporary and Historic Heart Failure Cohorts.

Background: In heart failure with reduced ejection fraction (HFrEF), a substantial proportion of deaths are arrhythmic. Implantable cardioverter-defibrillators (ICDs) are recommended for primary prevention in patients with left ventricular ejection fraction (LVEF) ≤ 35% despite guideline-directed medical therapy (GDMT), but landmark trials predate widespread use of angiotensin receptor-neprilysin inhibitors (ARNI) and sodium-glucose cotransporter 2 inhibitors (SGLT2i), raising uncertainty about arrhythmic risk in the contemporary treatment era. Methods: We retrospectively studied consecutive HFrEF patients undergoing primary-prevention ICD implantation at a single center (2015-2022), categorized into historical-era and contemporary-era cohorts by ARNI/SGLT2i adoption. Propensity-score matching balanced baseline characteristics. The primary endpoint was time to first appropriate ICD therapy (antitachycardia pacing or shock). Results: Of 289 patients (mean age 62 ± 11 years, 82% male), 234 (117 per group) remained after matching. Mean follow-up was 51 months. Appropriate ICD therapy incidence did not differ significantly between contemporary-era and historical-era cohorts (hazard ratio [HR] 1.52, 95% CI 0.84-2.72; Conclusion: ICD therapy rates were not significantly different between the contemporary-era and historical-era cohorts, a finding robust to sensitivity and competing-risk analyses. These results should be interpreted cautiously, as the study may be underpowered to detect modest differences, and clinically relevant effects cannot be excluded.