Objective To explore the relationship between coronary angiography before cardiac surgery and acute renal injury (AKI). MethodsThe patients who underwent coronary angiography within 30 days before cardiac surgery in the First Affiliated Hospital of Xi’an Jiaotong University from January 2015 to April 2019 were included. The baseline characteristics, clinical data and prognosis were collected for retrospective analysis. Postoperative AKI was defined according to KDIGO criteria. Univariate analysis and multivariate logistic regression analyses were used to explore the relationship between the interval from preoperative coronary angiography to cardiac surgery and postoperative AKI. ResultsFinally 1 112 patients were collected. The incidence of postoperative AKI was 40.8%, of which grade 2-3 AKI accounted for 11.9%. Multivariate analysis showed that age, body mass index and time interval between preoperative coronary angiography and cardiac surgery within 24 hours (OR=1.625, 95%CI 1.116-2.364, P=0.011) were independent predictors of postoperative AKI. The incidence of AKI in patients who underwent preoperative coronary angiography within 24 hours was 10.6%, higher than those more than 24 hours (P=0.004). Patients who underwent valve surgery with or without coronary artery bypass grafting (CABG) had a higher risk of AKI than those who only underwent CABG. The in-hospital stay of patients who developed AKI was 2 days longer than those without AKI. However, undergoing coronary angiography within 24 hours before cardiac surgery did not prolong the length of ICU stay or hospital stay, nor did it increase the risk of death or renal failure after the operation. Conclusion Undergoing coronary angiography within 24 hours before cardiac surgery increases the risk of postoperative AKI.