Use of the Hypoxia–Age–Shock Index at Triage to Predict Mortality in Geriatric STEMI Patients Undergoing Primary PCI

<i>Background and Objectives</i>: Older adults with ST-segment elevation myocardial infarction (STEMI) experience disproportionately high mortality despite advances in reperfusion therapy. The Shock Index (SI) and Age-Shock Index (ASI) offer rapid hemodynamic assessment but do not address hypoxia. The Hypoxia-Age-Shock Index (HASI), which incorporates oxygen saturation (SpO₂), may improve early mortality prediction in geriatric STEMI. <i>Materials and Methods</i>: This retrospective cohort study included adult STEMI patients receiving primary percutaneous coronary intervention (PCI) at a tertiary center from 2019 to 2023. A total of 711 patients were analyzed, including 254 aged ≥65 years. SI, ASI, and HASI were calculated using triage vital signs prior to intervention. The primary outcome was in-hospital mortality. Thirty-day mortality was analyzed as a pre-specified secondary endpoint using Kaplan-Meier survival analysis and multivariable Cox regression. Discrimination was assessed using ROC curves with pairwise AUC comparison by DeLong's test. <i>Results</i>: Elderly patients showed higher creatinine and troponin T levels, lower hemoglobin, and elevated ASI and HASI values (all <i>p</i> < 0.001). They had increased rates of cardiogenic shock (26.8% vs. 14.0%), major adverse events (26.0% vs. 10.1%), and in-hospital mortality (9.4% vs. 3.7%, <i>p</i> = 0.003). Age ≥ 65 years independently predicted 30-day mortality (adjusted HR 2.59, 95% CI 1.34-5.04). Among indices, HASI demonstrated the highest discriminative performance (AUC 0.703 in elderly; 0.743 in younger patients). <i>Conclusions</i>: In geriatric STEMI, HASI demonstrated numerically higher discriminative performance for in-hospital mortality compared with SI and ASI, supporting its use as a simple and rapid triage tool.