The prognostic value of shock index for the outcomes of acute myocardial infarction patients

BACKGROUND Several studies have revealed that high shock index (SI) is a risk factor for acute myocardial infarction (AMI) patients. These studies do not give a systematic review in this issue. Therefore, we conducted a systematic review and meta-analysis to determine the effect of high SI on the prognosis of AMI patients. METHODS We did a systematic search of PubMed, Embase, and the Cochrane Library, using various combinations of keywords such as "shock index," "shock-index," "acute myocardial infarction," "ST elevation myocardial infarction," "non-ST segment elevation myocardial infarction," "STEMI," "NSTEMI," "AMI," and "MI" for eligible studies published up to December 23, 2016. The 3 primary outcomes for this analysis were all-cause in-hospital mortality, short-term adverse outcomes, and long-term adverse outcomes. RESULTS Database searches retrieved 226 citations. Finally, 8 studies enrolling 20,404 patients were eventually included in the analysis. High SI was associated with an increased in-hospital mortality (pooled RR = 10.96, 95% CI: 2.00-59.94, P = .01). Adverse outcomes were significantly higher in the high SI group compared to the low SI group (pooled RR = 1.93, 95% CI: 1.10-3.39, P = .02; I = 95%). Individuals with high SI had an increased risk of long-term adverse outcomes (pooled RR = 2.31, 95% CI: 1.90-2.81, P < .001) compared to low SI. CONCLUSION High SI may increase the in-hospital mortality, short-term, and long-term adverse outcomes in AMI patients.