Shock Index and Modified Shock Index Are Predictors of Long-Term Mortality in STEMI and NSTEMI Patients

Background: Acute coronary syndromes (ACS), including STEMI and NSTEMI, are leading causes of mortality worldwide. The Shock Index (SI) and Modified Shock Index (MSI) are non-invasive markers traditionally used to assess hemodynamic status but their role in predicting long-term mortality in ACS patients is less understood. Objective: To evaluate the prognostic value of SI and MSI in predicting long-term mortality among patients with STEMI and NSTEMI. Methods: A prospective cohort study was conducted on 275 consecutive patients diagnosed with STEMI and NSTEMI at the Department of Cardiology, PIMS, Islamabad, between March 1, 2024, and July 31, 2024. Patients were divided into two groups: Group 1 (n=138) assessed using SI and Group 2 (n=137) using MSI. Follow-up for three years was conducted to record all-cause mortality. Data were analyzed using SPSS version 25.0, with Cox proportional hazards regression and Kaplan-Meier survival analysis employed to assess mortality risk. Results: During the three-year follow-up, mortality rates were 24.6% in the SI group and 26.3% in the MSI group. Higher SI and MSI values were significantly associated with increased mortality (SI HR=1.85, 95% CI: 1.35-2.54, p<0.001; MSI HR=2.10, 95% CI: 1.50-2.93, p<0.001). Conclusion: SI and MSI are significant predictors of long-term mortality in STEMI and NSTEMI patients and should be integrated into routine clinical assessments for better risk stratification.