Renal function at 1 year after cardiac transplantation rather than acute kidney injury is highly associated with long-term patient survival and loss of renal function - a retrospective cohort study.

This study aimed to assess the association between acute kidney injury (AKI), renal function 1 year after transplantation, and long-term adverse outcomes after cardiac transplantation. A retrospective cohort study was performed including 471 adult cardiac transplantation recipients that survived the first postoperative year between 1984 and 2012. Primary outcome variables were long-term overall and renal survival. During the first postoperative week, 40% (n = 188) of the recipients developed AKI stage I, 22% (n = 104) stage II, and 13% (n = 63) stage III, and 4% (n = 17) required temporary renal replacement therapy (RRT). No crude association was found between the development of AKI and long-term mortality (P = 0.50) or chronic RRT dependence (P = 0.27). In multivariable analysis, only AKI requiring RRT was associated with an increased risk for mortality (HR = 2.59, 95% CI = 1.17-5.73) and chronic RRT dependence (HR = 13.14, 95% CI = 3.26-52.92). While less severe episodes of AKI did not affect the recipient's long-term prognosis, renal function 1 year after transplantation had a strong association with long-term outcome. An eGFR <30 ml/min/1.73 was independently associated with mortality (HR = 2.69, 95% CI = 1.68-4.32) and an eGFR <60 ml/min/1.73 with chronic RRT dependence (eGFR 30-59: HR = 3.57, 95% CI = 1.41-9.01; eGFR <30: HR = 16.53, 95% CI = 5.72-47.78). In conslusion, besides AKI requiring RRT, less severe episodes of AKI have limited implications for the recipient's prognosis and long-term outcome after cardiac transplantation is strongly determined by the degree of renal impairment 1 year after transplantation.