Age shock index as an early predictor of cardiovascular death in acute coronary syndrome patients

Background The shock index (SI), reflecting heart rate (HR) to SBP ratio, is established for predicting adverse outcomes in acute coronary syndrome (ACS) patients. Exploring the age shock index (ASI), obtained by multiplying SI with age, could offer further insights into ACS prognosis. Objectives Assess ASI's effectiveness in predicting in-hospital death in individuals with ACS. MethodsThis study encompassed patients with acute myocardial infarction, drawn from a national registry spanning October 2010 to January 2022. The optimal ASI threshold was established using receiver operating characteristic (ROC) curve analysis. The primary outcome was in-hospital mortality. Results A total of 27 312 patients were enrolled, exhibiting a mean age of 66 +/- 13 years, with 72.3% being male and 47.5% having ST-elevation myocardial infarction. ROC analysis yielded an area under the curve (AUC) of 0.80, identifying the optimal ASI cutoff as 44. Multivariate regression analysis, adjusting for potential confounders, established ASI >= 44 as an independent predictor of in-hospital death [hazard ratio: 3.09, 95% confidence interval: 2.56-3.71, P < 0.001]. Furthermore, ASI emerged as a notably superior predictor of in-hospital death compared to the SI (AUC(ASI) = 0.80 vs. AUC(SI) = 0.72, P < 0.0001), though it did not outperform the Global Registry of Acute Coronary Events (GRACE) score (AUC(ASI) = 0.80 vs. AUC(GRACE) = 0.85, P < 0.001) or thrombolysis in myocardial infarction (TIMI) risk index (AUC(ASI) = 0.80 vs. AUC(TIMI) = 0.84, P < 0.001). Conclusion The ASI offers an expedient mean to promptly identify ACS patients at elevated risk of in-hospital death. Its simplicity and effectiveness could render it a valuable tool for early risk stratification in this population.