Chronic kidney disease can develop as a long-term complication after cardiac surgery—a condition associated with increased risk of new cardiovascular events, readmissions and mortality. Diagnosis is often delayed, as the condition is asymptomatic in early stages and post-discharge kidney follow-up is not routinely performed. We aimed to evaluate the occurrence and timing of chronic kidney disease after cardiac surgery in patients with normal preoperative kidney function and describe associated temporal trends in risk factors and mortality.

Patients undergoing cardiac surgery at Odense University Hospital, Denmark, between January 2000 and May 2022 were identified from the Western Denmark Heart Registry. Clinical data were extracted and merged with biochemical data from regional laboratory systems. Only the most recent operation was included in the analysis. Patients with pre-existing kidney disease and endovascular procedures were excluded.

A total of 13 299 patients were included. Median follow-up time was 88 months (42–141 months). Competing risk analysis revealed that 13.8% developed chronic kidney disease within 3 years after surgery and 18.8% within 5 years. Overall 90-day mortality was 3.6%, and 1-year mortality was 5.1%, with variations over time. During the observation period, patients became older and more comorbid, while preoperative kidney function improved. Postoperative acute kidney injury occurred in 25–30% of patients, with increasing severity over time.

Chronic kidney disease is a common and serious complication following cardiac surgery. Identification of patients in high risk of chronic kidney disease is important to develop post-discharge follow-up programs and improve patient outcomes.