Acute Kidney Injury and Outcome After Heart Transplantation

In Brief Background Kidney function is an important aspect for patient outcome after heart transplantation (HTX). Acute kidney injury (AKI) is defined by changes in serum creatinine (SCr) and diuresis with risk/injury/failure/loss/end stage (RIFLE), acute kidney injury network (AKIN), or kidney disease: improving global outcomes (KDIGO) scores. Methods We investigated the effect of perioperative AKI on 1-year mortality after HTX over a period of 10 years at a single-center university hospital. Multivariable Cox proportional-hazards regression analyzed the association between 1-year mortality and potential risk factors. Receiver operating curves for 1-year mortality were calculated to determine sensitivity and specificity of scores. Results Sixty of 346 patients (17%) died within the first year. Acute kidney injury was a predictor of mortality only in the high-risk AKI groups of all scores: Hazard ratios (95% confidence interval) for RIFLE F: 7.164 (3.307-15.523); KDIGO/AKIN stage 3: 3.492 (2.006-6.081). Within each score, we identified patient groups, which had no elevated risk for an adverse outcome despite their allocation to the milder forms of AKI. In multivariable regression analysis, primary graft dysfunction was the predominant perioperative risk factor for 1-year mortality. Conclusions In contrast to other patient cohorts, mild forms of perioperative AKI are of subordinate influence on patient outcome in HTX. Acute kidney injury (AKI) is common before and after heart transplantation. Only severe AKI is a predictor for on 1-year mortality in heart transplant patients. This has important implications for kidney allocation systems for other combined organ transplant patients such as kidney - liver transplant patients.