Novel Mortality Index Unveils Smoking's Role in STEMI Patients Undergoing Primary Percutaneous Coronary Intervention

Early risk stratification is crucial in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI). Conventional indices fail to fully capture the combined effects of hemodynamic compromise and hypoxemia. The Hypoxia-Age-Shock Index (HASI) integrates age, circulatory status, and peripheral oxygen saturation (SpO₂) and can be rapidly calculated at triage. In addition, the prognostic role of smoking remains controversial. We evaluated the ability of the HASI to predict in-hospital mortality and assessed the impact of smoking on short- and medium-term outcomes.

This retrospective cohort study included 711 STEMI patients (455 smokers, 256 non-smokers) treated with primary PCI from 2019 to 2022. Shock Index (SI), Age Shock Index (ASI) and HASI were calculated using vital signs and SpO₂. Mortality was assessed at 30 and 120 days. Logistic regression was used to identify independent predictors, and receiver operating characteristic curve analysis was used to compare predictive performance.

The HASI demonstrated superior discrimination for in-hospital mortality compared to the ASI and SI (area under the curve 0.747 vs. 0.700 and 0.628). At a cutoff of 0.524, the HASI showed high sensitivity (97.5%). Multivariable analysis identified HASI [odds ratio (OR) 8.14, 95% confidence interval (CI) 1.59-10.05] as an independent predictor; smoking was not significant (OR 0.81, 95% CI 0.36-1.84). Kaplan-Meier analysis showed comparable 30- and 120-day survival between smokers and non-smokers.

The HASI is a rapid, non-invasive, easily computed triage tool that outperformed conventional indices in predicting mortality in STEMI patients undergoing primary PCI in this study. Acute physiological derangements, rather than smoking, drove the outcomes. Its simplicity and speed make the HASI particularly valuable for immediate pre-laboratory risk stratification in high-volume or resource-limited emergency settings.