Prognostic Value of the Systemic Immune-Inflammation Index in Patients With Acute Myocardial Infarction: A Systematic Review and Meta-Analysis

The present review and meta-analysis evaluated the prognostic value of the Systemic Immune-Inflammation Index (SII) for patients with acute myocardial infarction (AMI) based on a search of PubMed, Embase, Cochrane Library, and Web of Science up to May 2024. Predefined inclusion and exclusion criteria were applied, with sensitivity and subgroup analyses performed to evaluate heterogeneity and assess the robustness of the findings. A total of 21 studies, including 13 771 patients with either ST-segment elevation myocardial infarction (STEMI) or non-ST-segment elevation myocardial infarction (NSTEMI), were analyzed. Higher SII levels were consistently associated with an increased risk of major adverse cardiovascular events (MACE) in AMI patients (odds ratio [OR]: 1.09; 95% confidence interval [CI]: 1.04-1.13; P < .0001) across various study designs, regions, and sample sizes. Elevated SII was significantly linked to MACE in STEMI patients, though not in NSTEMI patients. Additionally, high SII levels correlated AMI is divided into high SII group and low SII group. There is a significant correlation between the incidence of no-reflow in the high SII group with increased risks of no-reflow post-percutaneous coronary intervention (PCI), left ventricular adverse remodeling, and all-cause mortality, regardless of study factors (ie, research type, population characteristics, region, and sample size). Elevated SII is a significant predictor of adverse outcomes in AMI patients, especially for forecasting MACE in STEMI cases.