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.

Keywords: Systemic Immune-Inflammatory Index, Aged, 80 and over, Hospital Mortality, Multivariate Analysis, percutaneous coronary intervention, Predictive Value of Tests, Proportional Hazards Models, ROC Curve, Regression Analysis