Acute Kidney Injury as a Complication of Cardiac Transplantation: Incidence, Risk Factors, and Impact on 1-year Mortality and Renal Function

Background. Although chronic deterioration in renal function is frequently seen after cardiac transplantation, which is partly explained by the use of calcineurin inhibitors, data on the consequences of acute kidney injury (AKI) after cardiac transplantation are scarce. In the current study, the incidence of AKI and its impact onmortality and renal function was evaluated. Methods. Five hundred thirty-one cardiac transplant recipients (age >= 18 years) were evaluated for the postoperative incidence of AKI defined by the Kidney Disease Improving Global Outcome criteria. Secondary outcomes were renal function and mortality during the first postoperative year. Results. Overall, 405 (76%) recipients met the AKI criteria of which 211 (40%) had AKI stage I, 119 (22%) stage II, 75 (14%) stage III, and 25 patients (5%) required renal replacement therapy (RRT). One-year mortality rates in patients without AKI, stages I, II, and III were 4.8%, 7.6%, 11.8%, and 14.7%, respectively (log-rank test for trend, P = 0.008). In patients that required RRT 1-year mortality was 28.2% (log-rank test P = 0.001). In multivariable analysis only AKI requiring RRT was an independent predictor of 1-year mortality (hazard ratio, 2.75; P = 0.03). Improvement in renal function, compared with baseline values, occurred in 27% of recipients 1 month after transplantation. This was less likely to occur after previous AKI (P = 0.04). The AKI stages I to III were independently proportionally associated with a worse renal function 1 year after transplantation (P = 0.01). Conclusions. Acute kidney injury is highly frequent after cardiac transplantation, and the stage of AKI is associated with increased mortality and impaired renal function in the first postoperative year.