Impact of occult renal dysfunction on postoperative acute kidney injury and late prognosis in elderly patients undergoing coronary artery bypass

Preoperative occult renal dysfunction (PORD), defined as a normal serum creatinine (Scr) level with glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², may worsen outcomes after cardiac surgery. This study aimed to evaluate whether PORD is associated with adverse short- and long-term outcomes in elderly patients undergoing coronary artery bypass grafting (CABG). A retrospective analysis was conducted in 1,157 patients aged ≥ 70 years with normal Scr who underwent CABG at four centers. Patients were classified into PORD and control groups according to eGFR. Propensity score matching was used to balance preoperative characteristics. Logistic regression was performed to identify risk factors for postoperative acute kidney injury (AKI) and in-hospital mortality. Long-term survival was assessed using Kaplan–Meier analysis and Cox proportional hazards models. PORD was present in 29.3% of elderly patients with normal Scr. Compared with controls, the PORD group had higher preoperative Scr, higher rates of postoperative AKI (33.33% vs. 14.30%), and higher in-hospital mortality (6.19% vs. 3.55%). PORD independently predicted postoperative AKI and in-hospital mortality, and was associated with increased long-term mortality after CABG. Nearly one-third of elderly CABG patients with normal Scr have PORD, which is associated with a higher risk of postoperative AKI, in-hospital death, and long-term mortality. Routine eGFR assessment is recommended to improve preoperative renal risk stratification in this population. Not applicable.