Abstract: Objective To investigate the clinical prognostic value of neutrophils to lymphocyte ratio（NLR）in patients with ST-segment elevation myocardial infarction（STIMI）who underwent percutaneous coronary intervention（PCI）. Methods A total of 326 patients with acute ST segment elevation myocardial infarction were enrolled. According to the neutro⁃ phils to lymphocyte ratio, patients were divided into group T1（≤ 3.46）, group T2（3.47-6.75）and group T3（> 6.75）. Basic clinical data，laboratory indexes，coronary angiography results, TIMI grading and left ventricular ejection fraction（LVEF） were collected in all groups. Incidence of adverse events in hospital such as acute heart failure, thrombosis, ventricular tachy⁃ cardia and ventricular fibrillation, atrial fibrillation, atrioventricular block and cardiogenic shock, were recorded. Major ad⁃ verse cardiac events（MACE）, death of all causes, non-fatal MI, ischemic stroke and readmission due to heart failure at the 6-month follow-up were also noted. Results The incidence of heart failure, atrial fibrillation, ventricular tachycardia/ven⁃ tricular fibrillation and cardiogenic shock was higher in group T3 than those in the other two groups（P < 0.05）.The inci⁃ dence of multivessel coronary artery disease was significantly higher in group T3 than that in group T1 (54.1% vs 37.0%, P < 0.05). The percentage of TIMI grade 3 in post-operative infracted artery was significantly lower than that in group T1 (83.5% vs 94.4%). Left ventricular ejection fraction was significantly lower in group T3 than that of group T1 during hospital⁃ ization (0.48±0.10 vs 0.52±0.10). There was no significant difference in the incidences of death, non-fatal MI, ischemic stroke at 6 month follow up. But the rate of readmission due to heart failure was significantly higher in group T3 than that in the group T1（P < 0.05）. Conclusion Neutrophils to lymphocyte ratio may be a useful marker to predict the prognosis of pa⁃ tients with heart failure due to acute myocardial infarction.

Key words: myocardial infarction, lymphocytes, prognosis, heart failure, acute myocardial infarction, neutrophil-tolymphocyte ratio