Prognostic Value of the Endothelial Activation and Stress Index in Patients with Non-ST-Segment Elevation Myocardial Infarction.

BACKGROUND: Early risk stratification is essential in patients with non-ST-segment elevation myocardial infarction (NSTEMI). The Endothelial Activation and Stress Index (EASIX) reflects endothelial dysfunction and systemic stress; however, its prognostic value in NSTEMI remains unclear. This study aimed to investigate the association between EASIX and in-hospital mortality in patients with NSTEMI. METHODS: This retrospective, single-center observational study included 1001 consecutive NSTEMI patients hospitalized between January 2015 and August 2025. Endothelial Activation and Stress Index was calculated at admission using lactate dehydrogenase, creatinine, and platelet count. Univariable and multivariable logistic regression analyses were performed to identify independent predictors of in-hospital mortality. Discriminative performance was assessed using receiver operating characteristic analysis and Kaplan-Meier survival analysis. RESULTS: In-hospital mortality occurred in 41 patients (4.1%). Non-survivors had significantly higher EASIX values than survivors (median 1.76 vs. 0.94, P < .001). In multivariable analysis, EASIX (OR 1.66, 95% CI 1.24-2.23; P = .001), GRACE score (OR 1.04, 95% CI 1.03-1.06; P < .001), and revascularization (OR 0.37, 95% CI 0.15-0.55; P = .003) remained independent predictors of in-hospital mortality. EASIX demonstrated good discriminative ability (AUC 0.770), and higher levels were associated with worse survival. CONCLUSION: Endothelial Activation and Stress Index is an independent and practical predictor of in-hospital mortality in NSTEMI and may aid early risk stratification using routine laboratory data.