Shock Index More Sensitive Than Cardiogenic Shock in ST-Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention

BACKGROUND: Cardiogenic shock (CS) is a strong predictor of mortality in patients with ST-elevation myocardial infarction (STEMI), but there is evidence that shock index (SI), taking into account both blood pressure and heart rate, is a more sensitive and powerful predictor. We investigated the independent impact of SI and CS on 30-day and 1-year mortality in patients with STEMI, treated by primary percutaneous coronary intervention (PCI). METHODS AND RESULTS: In 7,412 consecutive patients with STEMI treated with primary PCI, the predictive value of either SI or CS on 1-year mortality was assessed. Best cut-off value of SI, determined using receiver operating characteristic (ROC) curve, was 0.7, with an ROC AUC of 0.66 (95% CI: 0.65-0.67), compared with an ROC AUC of 0.60 (95% CI: 0.59-0.61) for CS (P<0.001). At admission, 387 patients (5.2%) had CS and 1,567 patients (21.1%) had SI ≥0.7. The adjusted hazard ratio of mortality in patients with SI ≥0.7 and in CS patients was, respectively, 3.3 (95% CI: 2.4-4.6) and 3.1 (95% CI: 2.1-4.6) after 30 days, and 2.3 (95% CI: 1.8-2.9) and 3.1 (95% CI: 2.2-4.2) after 1 year. CONCLUSIONS: SI identifies more patients with increased risk of mortality, and seems to be a more sensitive prognostic predictor than CS in patients with STEMI treated by primary PCI.