Exploring Sex and Clinical Factors Associated with Long-Term Survival After Implantable Cardioverter-Defibrillator Implantation: A 10-Year Cohort Study

<b>Background</b>: Sex-related differences in outcomes after implantable cardioverter-defibrillator (ICD) implantation remain incompletely understood. Although women receive ICDs less frequently, whether their long-term survival differs from that of men in real-world clinical practice is not well established. We aimed to evaluate sex-specific mortality and relative survival in a large consecutive cohort of ICD recipients from a tertiary hospital. <b>Methods</b>: We conducted a retrospective cohort study including all consecutive patients who underwent ICD implantation at a tertiary hospital between 2015 and 2025. Demographic features, device indication, and mortality were obtained through clinical records. Relative survival (observed vs. expected) was estimated using the Ederer II method with national life tables. A Cox proportional hazards model assessed the effect of sex on mortality. <b>Results</b>: A total of 1091 patients (82.1% men; mean age 63.1 ± 13.1 years) were included. During a mean follow-up of 4.33 ± 3.22 years, 230 patients died (21.1%). Women showed lower unadjusted all-cause mortality than men: 24 deaths (18.0%) vs. 206 (20.6%). Women had significantly higher left ventricular ejection fraction (41.5 ± 23.6% vs. 37.2 ± 18.1%, <i>p</i> = 0.0046), less ischemic cardiomyopathy, and lower prevalence of cardiovascular risk factors. Although univariable analysis suggested lower mortality in women (HR 0.58, 95% CI 0.38-0.90; <i>p</i> = 0.014), multivariable analysis indicated that sex was not an independent predictor of mortality (HR 0.81, 95% CI 0.53-1.26). Relative survival revealed a substantial long-term mortality burden in ICD carriers, especially in men: men: 4-year survival 82.3% (expected 93.2%); 8-year 66.7% (85.6%); 12-year 56.0% (76.8%); women: 4-year survival 89.1% (expected 96.7%); 8-year 77.1% (92.8%); 12-year 77.1% (89.2%). <b>Conclusions</b>: In this large real-world cohort of ICD recipients, women showed lower unadjusted mortality and a smaller excess mortality compared with the general population. However, sex was not an independent predictor of survival after multivariable adjustment. These findings may indicate that observed survival differences are largely explained by differences in clinical profile and comorbidity burden rather than by sex itself.