Acute kidney injury after heart transplantation: importance of perioperative relative pulmonary hypertension and right ventricular dysfunction

Abstract

Introduction Acute kidney injury (AKI) after heart transplantation (HT) is a common complication, which can lead to subsequent chronic kidney disease, end-stage kidney disease requiring dialysis and higher risk of cardiovascular events post HT.1 The aim of the study is to determine the perioperative predictors of severe AKI after HT. The authors hypothesized that relative pulmonary hypertension (PH), defined by a ratio that relates mean arterial-to-mean pulmonary arterial pressure (MAP/MPAP) is a risk factor independently associated to post-HT severe AKI. Methods After obtaining Institutional Review Board approval, the authors retrospectively studied all consecutive adult patients who underwent HT between January 2009 and December 2017 at a tertiary care university hospital and followed-up with them until December 2019. Follow-up was accomplished for all patients. Patients included in the analysis had undergone first orthotopic HT and were 18 years or older. Patients who underwent an additional organ transplantation (kidney, liver, lung) before or concurrently with HT, and those who died within 24 hours after HT were excluded. According to KDIGO classification,2 patients were divided into 2 groups based on AKI severity developed within 7 days after HT: patients with severe AKI (stage 3) and patients with minor or non-AKI. P values Results During the study period, a total of 205 adult patients underwent HT. Patients who underwent previous heart (n=3) or kidney transplantation (n=1), combined transplantation (n=13, including 2 heart re-transplantations) or died within 24 hours after HT (n=6) were excluded. A total 184 patients met the inclusion criteria. Among the included patients, 83.2% (n=153) suffered from AKI, including 40.8% (n=75) AKI stage 1, 19.6% (n=36) AKI stage 2 and 22.8% (n=42) AKI stage 3. Twenty-nine patients (15.8%) required RRT in the postoperative period. Using multivariate logistic regression analysis, the independent risk factors related to AKI stage 3 after HT were preoperative relative PH (OR:1.62, 95% CI:1.05-2.49, p=0.028), central venous-to-pulmonary capillary wedge pressure ratio >= 0.86 (OR:3.59, 95% CI:1.13-11.43, p=0.030) and postoperative right ventricular dysfunction (OR:3.63, 95% CI:1.50-8.75, p=0.004). Conversely, preoperative estimated glomerular filtration rate (OR:0.99, 95% CI:0.97-1.00, p=0.143) was not related to AKI stage 3 after HT. Discussion In patients undergoing heart transplantation, severe AKI was more likely related to preoperative relative PH, central venous-to-pulmonary capillary wedge pressure ratio and postoperative RV failure than to preoperative estimated glomerular filtration rate. Early recognition of perioperative AKI risk factors in the HT setting may provide possibilities of prevention and treatment strategies.