Endothelial stress indices in acute coronary syndrome: comparative prognostic performance of EASIX and its variants

Abstract Objectives Endothelial dysfunction plays a pivotal role in the pathophysiology of acute coronary syndromes (ACS), contributing to vascular instability and impaired perfusion. The endothelial activation and stress index (EASIX), originally developed for hematologic conditions as a marker of endothelial stress, has recently attracted interest in cardiovascular prognostication. However, its utility in ACS remains insufficiently defined. This study aimed to evaluate the prognostic performance of the original EASIX and its simplified (s-EASIX) and modified (m-EASIX) variants in predicting 30-day in-hospital mortality in ACS patients. Methods We retrospectively analyzed 368 patients with ACS admitted to a coronary intensive care unit between June 2022 and June 2024. EASIX-based scores were calculated from admission laboratory parameters. The primary endpoint was all-cause in-hospital mortality, defined as death occurring during hospitalization or within 30 days of admission. Predictive accuracy was assessed using receiver operating characteristic (ROC) curve analysis, multivariate Cox regression, and model fit via Akaike information criterion (AIC). Results In-hospital mortality occurred in 19 patients (5.2 %). All three scores were significantly higher among non-survivors (p<0.01). m-EASIX demonstrated the highest AUC (0.818) and sensitivity (88.2 %), followed by EASIX (AUC: 0.789) and s-EASIX (AUC: 0.709). In multivariate Cox analysis adjusted for conventional clinical variables, all scores independently predicted mortality, with s-EASIX yielding the highest hazard ratio (HR=2.149; p<0.01). EASIX achieved the best model fit (AIC=123.123). Conclusions EASIX and its variants are independent predictors of short-term mortality in ACS. Among them, the original EASIX exhibited the most consistent overall performance, supporting its potential role in early risk stratification of critically ill cardiac patients.