Systemic Immune-Inflammatory Index Predicts Clinical Outcomes for Elderly Patients with Acute Myocardial Infarction Receiving Percutaneous Coronary Intervention

BACKGROUND We assessed the utility of the systemic immune-inflammatory index (SII) in estimating the in-hospital and long-term prognosis of elderly patients with acute myocardial infarction (AMI) who received percutaneous coronary intervention (PCI). MATERIAL AND METHODS Our study evaluated 711 consecutive elderly patients (age 65-85 years) from January 2015 to December 2017. The correlation between clinical outcomes and SII was analyzed through the stepwise Cox regression analysis and the Kaplan-Meier approach. The clinical endpoints were all-cause mortality and major adverse cardiovascular and cerebrovascular events (MACCE) in-hospital and during 3-year follow-up. RESULTS The study enrolled 711 elderly patients with AMI (66.95% male, 71.99±0.19 years). Kaplan-Meier analysis showed a lower survival rate in patients with higher SII scores, which also predicted in-hospital and long-term (≤3 years) outcomes. In multivariate analyses, SII showed an independent predictive value for in-hospital mortality (hazard ratio (HR), 3.32; 95% confidence interval (CI), 1.55-7.10; p<0.01), in-hospital MACCE (HR, 1.43; 95%CI, 1.02-2.00; p=0.04), long-term mortality (HR, 1.95; 95%CI, 1.23-3.09; p<0.01), along with long-term MACCE (HR, 1.72; 95%CI, 1.23-2.40; p<0.01). Moreover, SII showed a weak but significant positive relationship with the Gensini score among patients developing non-ST-segment elevation myocardial infarction (r=0.18; p<0.01). CONCLUSIONS SII, a readily available laboratory marker, is a potential indicator to predict the clinical endpoints for elderly patients with AMI undergoing PCI.