Systemic immune-inflammation index predicts in-hospital and long-term outcomes in patients with ST-segment elevation myocardial infarction

Objective This study examines the predictive value of the novel systemic immune-inflammation index (SII) in patients with ST-segment elevation myocardial infarction (STEMI). Methods A total of 1660 patients with STEMI who underwent primary percutaneous coronary intervention (pPCI) were enrolled in the study. In-hospital and 3-year outcomes were compared between the four groups (Q1-4). The SII was calculated using the following formula: neutrophil*platelet/lymphocyte. Results The frequency of in-hospital cardiogenic shock, acute respiratory failure, acute kidney injury, ventricular arrhythmia, stent thrombosis, recurrent myocardial infarction, major adverse cardiac events and mortality were significantly higher in the high SII groups (Q3 and Q4). Logistic regression models demonstrated that Q3 and Q4 had an independent risk of mortality and Q4 had an independent risk of cardiogenic shock compared to Q1. Receiver operating characteristic analysis showed that the best cutoff value of SII to predict the in-hospital mortality was 1781 with 66% sensitivity and 74% specificity. Kaplan-Meier overall survivals for Q1, Q2, Q3 and Q4 were 97.6, 96.9, 91.6 and 81.0%, respectively. Cox proportional analysis for 3-year mortality demonstrated that Q3 and Q4 had an independent risk for mortality compared to Q1. Conclusion SII, a novel inflammatory index, was found to be a better predictor for in-hospital and long-term outcomes than traditional risk factors in patients with STEMI undergoing pPCI.