Kidney disease and cardiac surgery: marker, mediator, or both?

Cardiac surgery places an enormous burden on the kidneys, and therefore, acute kidney injury (AKI) is a common postoperative complication. Pre-existing chronic kidney disease (CKD) is a strong predictor of cardiac surgery-associated AKI, in addition to the evidence of a bidirectional interaction where AKI also accelerates the progression of CKD and increases the risk of renal failure. While observational research links kidney dysfunction to prolonged hospital stays, morbidity, and mortality, the question remains whether AKI is a modifiable mediator or merely a perioperative risk predictor. Larger analyses, including that of Bille and colleagues, indicate that AKI drives the acceleration of CKD. These findings provide further evidence for systematic follow-up and early implementation of kidney-protective measures to optimise long-term renal function after cardiac surgery.