Bedside Prediction of 30-day Adverse Outcomes in ACS Using Shock Index, NLR, and Creatinine

Objectives: Early risk stratification in acute coronary syndrome (ACS) is crucial for guiding management and improving outcomes. Although established scores such as thrombolysis in myocardial infarction and Global Registry of Acute Coronary Events are widely used, their complexity and reliance on multiple parameters may limit practicality in emergency settings. We aimed to investigate whether a simple combination of three routinely available parameters, shock index (SI), neutrophil-to-lymphocyte ratio (NLR), and serum creatinine, could predict 30-day major adverse cardiovascular events (MACE) in ACS patients. Materials and Methods: This single-center retrospective cohort study included 500 consecutive ACS patients [ST-elevation myocardial infarction (STEMI), non-STEMI, unstable angina] admitted between January 2021 and December 2022. SI was calculated as heart rate divided by systolic blood pressure; NLR was obtained from a routine blood count; and serum creatinine was measured on admission. We evaluated the association of these parameters, individually and in combination, with 30-day MACE, defined as all-cause mortality, recurrent myocardial infarction, urgent target-vessel revascularization, or stroke. Logistic regression, ROC analysis, calibration plots, and decision curve analysis were performed. Results: Thirty-day MACE occurred in 56 patients (11.2%). SI ≥0.8 [odds ratio (OR): 2.10; 95% confidence interval (CI): 1.28-3.44], NLR ≥3 (OR: 1.85; 95% CI: 1.14-3.01), and creatinine >1.2 mg/dL (OR: 2.28; 95% CI: 1.39-3.75) were independent predictors. The model combining all three parameters demonstrated strong discriminative ability (area under the curve: 0.80; 95% CI: 0.74-0.85) and performed better than the individual parameters. Conclusion: The three-parameter model (SI, NLR, creatinine) provides a rapid, low-cost, and practical method for bedside risk stratification in ACS patients. This simple model demonstrates strong predictive accuracy for 30-day MACE and may serve as a complementary tool to established risk scores. Further multicenter studies are required to validate its utility.