In the Philippines, Acute Coronary Syndrome (ACS) is a major cause of mortality. Recognizing high-risk ACS patients quickly is crucial. The Modified Shock Index (MSI), a concise bedside risk scoring system, may enhance triaging by predicting short-term outcomes, facilitating a more aggressive approach for timely intervention.

The aim of this study is to determine MSI’s predictive value for in-hospital mortality in ACS patients, comparing its sensitivity and specificity to Thrombolysis In Myocardial Infarction (TIMI) risk scoring. It also intends to determine association between MSI and major adverse cardiovascular events (MACE).

This retrospective cohort study was conducted in a tertiary hospital with 172 patients aged 18 and above admitted for ACS from January 2017 to December 2022, focused on in-hospital mortality as the primary outcome and other MACE as secondary outcomes. Chi-square test customized for multiple response sets was done to determine association between MSI and clinical outcomes. The study employed ROC analysis for MSI, generating a curve to illustrate sensitivity-specificity trade-offs, Youden Index determined to identify optimal cut-off points, and DeLong’s test to compare efficacy of MSI and TIMI.

A high MSI (≥1) was significantly and independently linked to in-hospital all-cause mortality in ACS patients (p < 0.001). MSI exhibits 82.35% sensitivity and 82.89% specificity for predicting in-hospital mortality. Chi-square test customized for multiple response sets revealed statistically significant association between MSI and the occurrences of cardiogenic shock, revascularization, life-threatening arrhythmia, and cardiac arrest. ROC analysis reveals MSI and TIMI scores as strong predictors (AUC values: 0.848 and 0.787 respectively), with comparable performance indicated by the DeLong test.

MSI proved a reliable parameter for predicting in-hospital mortality in patients presenting with ACS in Notre Dame de Chartres Hospital.