Determinants of Long-Term Mortality in Patients with Acute Coronary Syndromes Requiring CICU Admission: Diagnosis Versus Vulnerability in a Contemporary Real-World Cohort

Background: Contemporary cardiac intensive care units (CICUs) increasingly care for elderly and multimorbid patients, yet the relative contribution of admission diagnosis versus underlying comorbidity burden to long-term prognosis remains unclear. We aimed to identify independent determinants of 5-year mortality following emergent CICU admission, with particular focus on acute coronary syndromes (ACS). Methods: We retrospectively analyzed 1299 consecutive adults admitted emergently to a tertiary CICU between 2017 and 2019. Baseline characteristics, comorbidities, and in-hospital management were assessed. Five-year follow-up was available for 825 patients with ACS. Survival was evaluated using Kaplan–Meier analysis and Cox proportional hazards models to identify independent predictors of all-cause mortality. Results: ACS accounted for 63.3% of admissions. In-hospital mortality was 8.0%, without sex-related differences. At 5 years, cumulative mortality among ACS patients was 25.9% and differed across subtypes, being highest in non-ST elevation myocardial infarction (NSTEMI, 31.1%) compared with unstable angina (24.0%) and ST elevation myocardial infarction (STEMI, 18.4%) (p < 0.001). However, after multivariable adjustment, ACS subtype and sex were not independently associated with mortality. Instead, older age (HR per year increase), atrial fibrillation, and prior stroke and Charlson Comorbidity Index emerged as the strongest predictors of death. Conclusions: In a contemporary, real-world CICU cohort, long-term survival was determined predominantly by age and comorbidity burden rather than by ACS phenotype or sex. These findings support a shift from diagnosis-centered to risk-profile-based long-term stratification following emergent intensive cardiac care.