Abstract

Background and Objectives: Risk stratification is an important tool for guiding clinical decision-making in patients with non-ST-segment elevation myocardial infarction (NSTEMI), yet mortality remains considerable despite contemporary therapeutic advances. Endothelial Activation and Stress Index (EASIX), calculated using lactate dehydrogenase, serum creatinine, and platelet count, is a readily available composite prognostic index that has demonstrated prognostic value across various cardiovascular settings. However, its role in NSTEMI has not been fully established. We therefore evaluated the association between EASIX and 1-year mortality and examined whether it provides incremental prognostic information beyond the GRACE risk score. Materials and Methods: We retrospectively evaluated 624 consecutive patients with NSTEMI who underwent invasive coronary angiography. EASIX was calculated from laboratory parameters obtained at admission. The prognostic significance of EASIX was evaluated using Cox proportional hazards models, Kaplan–Meier survival analysis, restricted cubic spline modelling, and incremental performance metrics. Results: During 1-year follow-up, 75 patients (12.0%) died. Admission EASIX values were higher among non-survivors than survivors (p < 0.001). Mortality increased progressively across EASIX tertiles (p < 0.001). In multivariable analyses, log2(EASIX) remained independently associated with mortality both in the clinical model (HR 1.381, p = 0.002) and after adjustment for the GRACE score (HR 1.315, p = 0.005). Restricted cubic spline analyses supported a graded relationship between EASIX and mortality risk. Addition of EASIX to the GRACE score improved discrimination (ΔAUC = 0.015, p = 0.032) and risk reclassification (continuous NRI = 0.385, p = 0.020). Conclusions: Admission EASIX emerged as an independent predictor of 1-year mortality among patients with NSTEMI. Furthermore, it provides incremental prognostic information beyond the GRACE risk score and may represent a simple, inexpensive, and readily available tool for risk stratification in contemporary NSTEMI practice.

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