Objective To investigate the correlation between the inflammatory burden index(IBI)and major adverse cardiovascular events(MACEs)in patients with ST-segment elevation myocardial infarction(STEMI)after percutaneous coronary intervention(PCI),and to assess the efficacy of IBI in predicting in-hospital and long-term MACEs.Methods This retrospective study included 465 STEMI patients who received PCI treatment in No.904 Hospital of Joint Logistics Support Force of PLA from Dec.2017 to Dec.2021.The IBI was calculated for each patient.The predictive value for in-hospital and long-term MACEs was evaluated using receiver operating characteristic(ROC)curves,and the area under curve(AUC)was calculated.The population was grouped based on the optimal IBI cut-off value for clinical characteristic analysis.Multivariate logistic regression and Cox regression analyses were used to identify factors independently associated with MACEs.The Kaplan-Meier estimator and log-rank test were used to assess the MACE risk of different IBI groups.Results The AUC value for predicting MACEs during hospitalization in STEMI patients using IBI was 0.687,and the AUC value for predicting long-term MACEs was 0.634.Multivariate logistic regression analysis revealed that a high IBI 102.33 mg/L)independently increased the risk of MACEs during hospitalization in STEMI patients(odds ratio=10.900,95％confidence interval[95％CI]4.273-29.180,P＜0.001).Multivariate Cox regression analysis further indicated that during long-term follow-up of STEMI patients,a high IBI(≥55.88 mg/L)independently predicted MACEs(hazard ratio=1.989,95％CI 1.128-3.506,P=0.018).Conclusion IBI is a valuable predictor for the occurrence of MACEs during hospitalization and long-term follow-up after PCI in STEMI patients.