Introduction: Acute kidney injury (AKI) is a frequent complication of heart transplantation (HT) with a reported incidence of 14-76%. Data on the clinical consequences of AKI among HT recipients are scarce. The aim of this study was to investigate the incidence of AKI in the early postoperative period after HT and to find out its related risk factors and its impact on clinical consequences.
Materials and Methods: A single center retrospective evaluation of data from 83 HT recipients (age >14 years) was performed for the postoperative incidence of AKI as defined by the Kidney Disease Improving Global Outcome (KDIGO) criteria. Moreover, risk factors for developing AKI were also analyzed. The requirement of renal replacement therapy (RRT) and mortality were evaluated as secondary clinical consequences.
Results: At the time of HT, the mean age of the patients was 37.9 ± 15.5 y, and 75% of the patients were male. Postoperative AKI was seen in 53 recipients (63.9%) of which 19 (35.8%) had AKI stage I, 20 (37.8%) stage II, 14 (26.4%) stage III. Thirty-nine patients (73.6%) required RRT; continuous RRT in 30 (76.9%), intermittent hemodialysis in 9 (23.1%). The recipients who had AKI were significantly older (40.7 ± 14.5 vs 32.8 ± 16.3 y; p=.018), had higher body mass index (24.0 ± 5.3 vs 21.6 ± 4.2; p=.028) and more frequent history of coronary artery disease (43.4% vs 20%; p=.035) and higher EuroSCOREs (9.9±9.0 vs 5.3±4.9; p=.01).  Higher pulmonary artery pressure and lower ejection fraction at the preoperative period; lower urine output, longer duration of cardiopulmonary bypass, higher doses of adrenaline requirement intraoperatively; and higher amount of erythrocyte, platelet and albumin infusion at the postoperative period were found in the recipients developing AKI when compared who did not (p<.05).  EuroSCORE, low urine output during surgery, postoperative higher amount of platelet suspension and albumin infusion were found as independent risk factors for AKI (Table 1).  One-year mortality was significantly higher among HT recipients with AKI (39% vs 13%: p=.02).
Conclusion: Our results demonstrated that the incidence of AKI in the early postoperative period after HT was 63.9%, and approximately two thirds required RRT. Among HT recipients, higher EuroSCORE, intraoperative low urine output, and postoperative higher amount of platelet suspension and albumin infusions were associated with AKI development.