Postoperative acute kidney injury increases short- and long-term death risks in elderly patients (≥ 75 years old) undergoing coronary artery bypass graft surgery

Abstract

Abstract Purpose To explore the incidence of postoperative acute kidney injury (AKI) after coronary artery bypass grafting (CABG) in elderly Chinese patients (≥ 75 years old) and its impacts on the short- and long-term prognosis. Methods A total of 493 patients aged 75–88 years old who underwent CABG from two medical centers between January 2006 and October 2021 were involved. Perioperative (preoperative and 7 days after operation) serum creatinine (Scr) levels were measured in all the enrolled patients. Univariate and multivariate logistic regression analyses were conducted to explore the independent risk factors of postoperative in-hospital mortality. Kaplan–Meier curves and COX model were used to test the risk factors of all-cause death during follow-up. Propensity score matching was used to balance differences between AKI and control groups. The primary outcome event was in-hospital death, and the secondary outcome was all-cause death during follow-up. Results The 198 patients were diagnosed with postoperative AKI. Intra-aortic balloon pump (IABP), cardiopulmonary bypass, and postoperative AKI were independent risk factors of in-hospital death. Gender, New York Heart Association Classification, preoperative eGFR, last eGFR within 7 days after operation, postoperative AKI, and postoperative renal function all impacted long-term prognosis. After 1:1 matching, 190 patients were included in the AKI and control groups. Use of IABP, use of cardiopulmonary bypass, and occurrence of postoperative AKI were still independent risk factors of in-hospital death. Preoperative eGFR, last eGFR within 7 days after operation, postoperative AKI and postoperative renal function all impacted long-term prognosis. Conclusion The incidence of postoperative AKI in elderly patients undergoing CABG is high, and postoperative AKI is an independent risk factor of both short- and long-term postoperative prognosis.