Background:Previous studies of contrast-induced acute kidney injury (CI-AKI) were mostly based on selective percutaneous coronary intervention (PCI) cases,and risk factors of CI-AKI after emergency PCI are unclear.The aim of this study was to explore the risk factors of CI-AKI in a Chinese population undergoing emergency PCI.Methods:A total of 1061 consecutive patients undergoing emergency PCI during January 2013 and June 2015 were enrolled and divided into CI-AKI and non-CI-AKI group.Univariable and multivariable analyses were used to identify the risk factors of CI-AKI in emergency PCI patients.CI-AKI was defined as an increase in serum creatinine ≥25％ or ≥0.5 mg/dl (44.2 tmol/L) above baseline within 3 days after exposure to contrast medium.Results:The incidence of CI-AKI in patients undergoing emergency PCI was 22.7％ (241/1061).Logistic multivariable analysis showed that body surface area (BSA) (odds ratio [OR] 0.213,95％ confidence interval [CI]:0.075-0.607,P =0.004),history of myocardial infarction (MI) (OR 1.642,95％ CI:1.079-2.499,P =0.021),left ventricular ejection fraction (LVEF) (OR 0.969,95％ CI:0.944-0.994,P =0.015),hemoglobin (Hb) (OR 0.988,95％ CI:0.976-1.000,P =0.045),estimated glomerular filtration rate (OR 1.027,95％ CI:1.018-1.037,P ＜ 0.001),left anterior descending (LAD) stented (OR 1.464,95％ CI:1.000-2.145,P =0.050),aspirin (OR 0.097,95％CI:0.009-0.987,P =0.049),and diuretics use (OR 1.850,95％ CI:1.233-2.777,P =0.003) were independent predictors of CI-AKI in patients undergoing emergency PCI.Conclusion:History of MI,low BSA,LVEF and Hb level,LAD stented,and diuretics use are associated with increased risk of CI-AKI in patients undergoing emergency PCI.