Objective:To investigate the risk factors of major adverse cardiovascular events(MACE)in patients with early-onset acute coronary syndrome(ACS)after emergency percutaneous coronary intervention(PCI)during hospitalization.Methods:Clinical data of 234 patients who were diagnosed with early-onset ACS and received emergency PCI in the Affil-iated Hospital of Southwest Medical University between January 2019 and December 2021 were retrospectively analyzed.According to the occurrence of MACE during hospitalization,the patients were divided into no MACE group(n=130)and MACE group(n=104),and the clinical data were compared between two groups.Multivariate Logistic regression was used to analyze the risk factors of MACE in patients with early-onset ACS after PCI during hospitalization.Results:Compared with those in no MACE group,patients in MACE group had significant higher age[49(45,53)years vs.52(47,55)years],proportions of hypertension(41.5%vs.66.4%)and multi-vessel coronary disease(50.8%vs.67.3%),levels of aspartate aminotransferase(AST)[118.8(58.1,222.1)U/L vs.179.0(72.1,306.5)U/L],creatinine[64.0(54.1,72.9)μmol/Lvs.70.9(59.5,84.0)μmol/L],D-dimer(D-D)[0.3(0.2,0.5)mg/L vs.0.7(0.3,1.7)mg/L]and peak N terminal pro brain natriuretic peptide(NT-proBNP)[188.0(100.0,570.8)pg/ml vs.2044.5(688.0,3527.8)pg/ml],and significant lower hemoglobin(Hb)level[148(139,156)g/L vs.139(126,155)g/L(P<0.05 or<0.01).Multivariate Logistic regression analysis indicated that hypertension(OR=3.711,95%CI 1.450~9.500,P=0.006),D-D(OR=2.385,95%CI 1.353~4.206,P=0.003)and NT-proBNP peak level(OR=1.002,95%CI 1.001~1.003,P<0.001)were independent risk factors for MACE in early-onset ACS patients after emergency PCI during hospitalization.Conclusion:Hypertension,D-D and NT-proBNP peak level could independently predict the short-term poor prognosis of patients with early-onset ACS after emergency PCI.Early intervention should be carried out to improve the prognosis of patients.