Age-modified shock index for predicting in-hospital outcomes in patients with ST elevated myocardial infarction undergoing primary percutaneous coronary intervention

Early risk stratification in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) is crucial for timely identification of high-risk patients. Bedside indices derived from routinely available hemodynamic parameters, such as the shock index (SI), modified shock index (MSI), and age-modified shock index (A-MSI), have emerged as simple tools for risk assessment. This study aimed to compare the bedside SI, MSI, and A-MSI as simple and effective predictors of in-hospital mortality in patients with STEMI undergoing primary PCI. A sample of consecutive STEMI patients who underwent primary PCI were included. The SI was calculated as heart rate (HR) ÷ systolic blood pressure (SBP). The MSI was computed as HR÷mean arterial pressure (MAP), with MAP calculated as (2×diastolic blood pressure + SBP)/3. A-MSI was computed as age×MSI. Target outcome was in-hospital mortality. A total of 746 patients were included out of which 532 (71.3%) were male and mean age was 58.6 ± 11.3 years. In-hospital mortality was observed in 39 (5.2%) patients. The area under the curve (AUC) for the prediction of in-hospital mortality for SI was 0.662 [0.564–0.760], MSI was 0.692 [0.601–0.782], Age-MSI was 0.726 [0.644–0.809], and TIMI score was 0.636 [0.534–0.738]. The optimal cutoff value for SI was ≥ 0.845 with an AUC of 0.659 [0.566–0.752], MSI ≥ 1.05 has AUC of 0.658 [0.567–0.748], Age-MSI ≥ 70 has AUC of 0.667 [0.572–0.762], and TIMI ≥ 5 has AUC of 0.613 [0.526–0.701]. The age-adjusted index, A-MSI, offer a simple yet moderately predictive tool for identifying STEMI patients at high risk for in-hospital mortality. These indices can serve as valuable screening tools to stratify high-risk patients during their hospital stay.