The role of shock index in predicting adverse events in elderly patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention

Background The prognostic value of shock index(SI)in elderly patients with ST-segment elevation myocardial infarction(STEMI)is unclear.This study was to explore the association of shock index with long-term mortality in elderly STEMI patients undergoing percutaneous coronary intervention(PCI).Methods A total of 731 elderly patients with STEMI undergoing PCI were included and divided into three groups according to the tertiles of shock index:<0.58(n=241),0.58-0.71(n=233)and≥0.71(n=257).Shock index is the ratio of heart rate to systolic blood pressure.Receiver operating characteristic(ROC)curves were conducted and the area under the curve(AUC)of SI for predicting in-hospital mortality was calculated.The association of shock index with in-hospital and one-year mortality was evaluated using multivariate regression analysis.Results In patients with shock index in the first to third tertiles,in-hospital death occurred in 2.5%,4.3%and 11.3%of patients,respectively.Inhospital major adverse clinical events(MACEs)occurred in 8.7%,10.3%and 21.4%of patients,respectively.ROC analysis showed that shock index>0.74 was the best threshold for predicting in-hospital death.Shock index>0.74 was independently associated with increased risk of in-hospital death[adjusted odds ratio(OR):3.68,95%confidence interval(CI):1.85-7.32,P<0.001].Kaplan-Meier survival curves showed that patients with shock index>0.74 had a worse prognosis than those with shock index≤0.74(Log-rank test:33.58,P<0.001).Conclusions In elderly patients with STEMI undergoing PCI,elevated shock index was independently associated with in-hospital and one-year mortality.