Abstract 1795: Impact of Donor Ischemic Time on Early Outcomes After Pediatric Heart Transplantation: Analysis of Data From the United Network for Organ Sharing
Background: Previous studies using graft ischemic time either as a continuous variable or with arbitrary cut-off values have not demonstrated its association with post-transplant survival in pediatric heart transplant (HT) recipients. We hypothesized that ischemic time will have a threshold relationship with short-term outcomes after HT in children. We sought to determine whether graft ischemic time is independently associated with early survival post-HT.
Methods: In this retrospective multi-center cohort study using the Organ Procurement and Transplant Network data, all children <18 years of age undergoing first HT between 1987 and 2008 were included. The association of ischemic time with post-HT survival was explored using restricted cubic spline to allow for the most flexible relationship with outcome and further analyzed using ischemic time quartiles and Cox-proportional hazards modeling. The primary outcome variable was early graft loss (death or re-transplant within 6 months post-HT).
Results: Of 4,483 children transplanted, the median age was 3 years (IQR 0 to 12), 1885 (42%) had congenital heart disease (CHD), 933 (21%) were ventilated, 251 (5.6%) were on ECMO, and 66 (1.4%) required dialysis. The median ischemic time was 3.5 hrs (Inter-quartile range 2.7 to 4.3 hrs). Children with longer ischemic time were more likely to be younger, have CHD, renal dysfunction, elevated bilirubin, and to be on PGE support. In multivariable analysis, ischemic time >3.5 hours was associated with a 30% increase in graft loss by 6 months post-HT (hazard ratio 1.3; 95% confidence interval 1.1, 1.5, P=0.008) after adjusting for recipient and donor age, gender, diagnosis, prior sternotomy, level of hemodynamic support, renal dysfunction, bilirubin, and era of transplant. The higher risk of graft loss was similar for the third and the fourth quartiles of ischemic time. There was no interaction of ischemic time with recipient or donor age, or with cardiac diagnosis for graft loss.
Conclusions: Ischemic time beyond 3.5 hours was associated with a 30% increase in graft lost by 6 months after HT in children after adjusting for patient factors. This relationship between ischemic time and graft loss should be considered in developing risk-prediction models for post-HT survival.