Prevalence and Relevance of Acute Kidney Injury after Pediatric Heart Transplantation

Objectives: Acute kidney injury (AKI) is a frequent complication following cardiac surgical procedures. Its prognostic relevance after cardiac surgery in adults is well characterized. Contrarily, the relevance of AKI after pediatric cardiac surgical procedures is less clear. Heart transplantation (HTx) carries a high risk of perioperative AKI due to various reasons. We aimed to characterize the occurrence of AKI following pediatric HTx and its relevance for short- and long-term outcomes.

Methods: All patients who underwent HTx at one institution at an age of <18 years between 01/2003 and 12/2017 were included. The occurrence of AKI was observed until postoperative day 10. AKI was defined according to the KDIGO (kidney disease: improving global outcomes) criteria. Regression analysis was conducted to identify perioperative predictors of AKI. Long-term outcome functions were calculated using Kaplan–Meier estimation.

Result: A total of 104 consecutive patients underwent HTx at a median age of 6.2 years (IQR: 0.75–12 years) after a median listing time of 108 days (IQR: 15–131 days). The indications for HTx were cardiomyopathies in 53% and structural heart defects in 47% of patients, respectively. Postoperative AKI occurred in 82% of patients, thereof AKI stage 1 in 32%, stage 2 in 28%, and stage 3 in 22%. Hemodialysis was necessary in 5.8% of patients, and peritoneal dialysis in 1 patient (1%). 81% of the AKI occurred on the first (54%) or second (27%) postoperative day. Older patients developed more severe AKI stages (median age no AKI: 3.43 ± 4.8 years, stage 1: 4.82 ± 5.2 years, stage 2: 7.55 ± 6.3 years, stage 3: 8.82 ± 6.1 years; p = 0.006). Thirty-day mortality rates rose with increasing AKI stage (no AKI: 0%, stage 1: 0%, stage 2: 3.7%, stage 3: 8.7%; p = 0.04). The follow-up was complete for 100% of patients, and the median follow-up duration was 6.8 years. Overall 10-year survival was 87%. Postoperative AKI tended to be associated with reduced 10-year survival (no AKI: 93%, stage 1: 92%, stage 2: 88%, stage 3: 73%: p = 0.055). Pre-HTx mechanical ventilation was the only independent predictor for AKI stages 2 or 3 (OR: 22, 95% CI: 3.5–34). Interestingly, pre-HTx mechanical circulatory (MCS) support was associated with reduced occurrence of AKI stages 2 or 3 (no MCS: 55% AKI, MCS: 10% AKI).

Conclusion: AKI occurs frequently in the immediate postoperative course after pediatric HTx. Particularly older children are at risk. More severe AKI stages (KDIGO 2 and 3) are associated with reduced short- and long-term survival.

Publication History

Article published online:
19 February 2021