Acute kidney injury following cardiac surgery in elderly patients: A retrospective cohort study

Background As the global population ages rapidly, the number of elderly patients requiring cardiac surgery increases annually. Acute kidney injury (AKI) is one of the most common complications following cardiac surgery. However, the clinical characteristics of cardiac surgery-associated AKI (CSA-AKI) in elderly patients have not been fully elucidated. Methods A retrospective study was conducted on elderly patients who underwent cardiac surgery at a tertiary referral teaching hospital in China. We investigated the incidence and risk factors of CSA-AKI in this population. Results Among 2291 elderly patients undergoing cardiac surgery, 633 (27.6%) developed AKI, with incidences of 20.2% (462/2291), 6.1% (140/2291), and 1.4% (31/2291) for AKI stages 1-3, respectively. Patients undergoing aortic procedures exhibited the highest AKI incidence (42.8%, 83/194). Independent risk factors included advanced age, hypertension, anemia, complex surgical procedures, prolonged cardiopulmonary bypass (CPB) duration, postoperative cardiogenic shock and intraoperative renal hypoperfusion. The differences in CSA-AKI incidence across surgical categories were mainly related to hemoglobin levels and CPB duration. For modifiable risk factors, hemoglobin levels should be maintained above 115 g/L, and CPB duration should be minimized to mitigate the risk of CSA-AKI. At discharge, 515 of 615 surviving CSA-AKI patients achieved complete renal recovery, while 21 experienced partial recovery. Conclusions AKI is prevalent among elderly cardiac surgery patients. Risk reduction strategies should focus on preoperative anemia correction, intraoperative renal perfusion optimization, CPB time reduction, and prevention of cardiogenic shock. Short-term prognosis in elderly CSA-AKI patients is generally favorable.