Abstract 14939: Changes in Estimated Glomerular Filtration Rate After Retransplantation in Children and Young Adults

Introduction: Estimated glomerular filtration rate (eGFR) is abnormal in pediatric heart transplant (HT) patients with graft failure due to hemodynamic compromise and exposure to nephrotoxins. We aimed to evaluate differences in eGFR between primary HT (PT) and repeat HT (RT) in children and young adults. We hypothesized that eGFR will recover to baseline after HT, but RT will tend to have lower eGFR than PT. Methods: We reviewed all HT at our center from 1995-2021. eGFR was derived from the CKid U25 equation. eGFR was measured pre-HT, 1 week post-HT (peak creatinine), 1-3, 6, and 12 months post-HT, and most recent follow-up. We matched PT with RT patients based on age at HT, sex, and race. Changes in eGFR were measured within and between patients using a linear mixed effect model. Additionally, changes in eGFR were stratified between those with pre-HT eGFR < 60mL/min/1.73m2 and >= 60mL/min/1.73m2. We evaluated for associations between changes in eGFR and the number of rejections prior to RT, diagnosis, pre-HT eGFR, dialysis, prior VAD/ECMO support, waitlist time, bypass time, ischemic time, length of stay, time from HT, graft loss, and nephrotoxin exposure. Results: RT was performed in 47 patients (early death N=1). Table 1 shows characteristics of the matched PT (n=36) and RT (n=36) cohort. Figure 1 compares PT and RT mean eGFR at the specified time points. Those with a pre-retransplant eGFR < 60mL/min/1.73m2 rebounded to levels significantly higher than pre-retransplant (p< 0.001). RT eGFR was lower than PT eGFR, but RT eGFR rebounded to levels significantly higher than prior to RT (p<0.001). There were no associations between changes in eGFR and bypass time, ischemic time, length of stay, or graft loss. Conclusions: eGFR falls transiently early after both PT and RT but rebounds back to baseline in PT or above baseline in RT. These findings help to characterize expected changes in renal function after PT and RT and guide expectations for renal recovery afterwards.