Impact of size matching on survival post-heart transplant in infants: Estimated total cardiac-volume ratio outperforms donor-recipient weight ratio

Abstract

PurposeCardiac volume-based estimation offers an alternative to donor-recipient weight ratio (DRWR) in pediatric heart transplantation (HT), but has not been correlated to post-transplant outcomes We sought to determine whether estimated Total Cardiac Volume (eTCV) ratio is associated with HT survival in infants. MethodsThe UNOS database was used to identify infants (age:<1year) who received HT in 1987-2020. Donor and recipient eTCV were calculated from weight using previously published data. Patient cohort was divided according to the significant range of eTCV ratio; characteristics and survival were compared. Results2845 infants were identified. Hazard ratio with cubic spline showed prognostic relationship of eTCV ratio and DRWR with the overall survival. The cut-point method determined an optimal eTCV ratio range predictive of infant survival was 1.05-1.85 whereas no range for DRWR was predictive. 75.6% patients had an optimal TCV ratio, while 18.1% were in the lower (LR) and 6.3% in the higher (HR) group. Kaplan-Meier analysis showed better survival for patients within the optimal vs LR (p=0.0017), and a similar significantly better survival when compared to HR (p=0.0053). The optimal eTCV ratio group (n=2151) had DRWR ranging from 1.09-5; 34.3% had DRWR 2-3, and 5.0% DRWR>3. ConclusionCurrently, an upper DRWR limit has not been established in infants. Therefore, determining the optimal eTCV range is important to identifying an upper limit that significantly predicts survival benefit. This finding suggests a potential increase in donor pool for infant recipients since over 40% of donors in the optimal eTCV range includes DRWR values>2 that are traditionally not considered for candidate listing.