Elevated shock index and modified shock index are associated with mortality and major adverse cardiac events in patients with acute myocardial infarction: A systematic review and meta-analysis

Background: Blood pressure (BP) and heart rate (HR) have been studied extensively to predict unfavourable outcomes in patients suffering from an acute myocardial infarction (AMI). Shock index (SI) and modified shock index (MSI) are two new emerging parameters that incorporate BP and HR into their calculations, thereby improving the predictive value of each HR and BP alone in AMI patients. Thus, our aim was to determine the prognostic utility of SI and MSI in AMI patients. Methods: We searched PubMed, ProQuest, EBSCO Host, and Europe PMC from conception to May 2022. Studies were eligible if they evaluated the relationship of SI and MSI with all-cause mortality and major adverse cardiac events. Results: A total of 16 studies involving 80,195 participants met the inclusion criteria and were included in this meta-analysis. Our study revealed significantly higher all-cause mortality risk for patients with high SI and MSI compared to patients with low indices, regardless of the periods of outcomes, study population, or diverse cut-off values. Moreover, both increased SI and MSI also predicted higher major adverse cardiac event rates. Conclusions: According to our findings, both SI and MSI in the emergency department can predict all-cause mortality and major adverse cardiac events in patients with acute myocardial infarction. Given this growing body of evidence, as well as the fact that SI and MSI are very simple objective indices derived from two readily available vital signs, they should be used in daily clinical practice to risk stratify patients presenting with acute myocardial infarction. PROSPERO registration CRD42022329558 .