Size Matching by Height, Body Surface Area, and Body Mass Index in Infant Heart Transplantation

Abstract

<h3>Purpose</h3> Congenital heart disease is the most common primary indication for transplantation in the infant population. Weight is the traditional metric for size-matching for infants but may fluctuate due to failure to thrive and fluid retention. We sought to analyze height, body surface area, and body mass index as possible alternative size-matching metrics in the infant population. <h3>Methods</h3> The UNOS database was retrospectively analyzed for infants (<1 years old) undergoing heart transplantation. 2115 infants were divided into quintiles (Q1-Q5) based on donor-to-recipient height ratio (DRHR), weight ratio (DRWR), Haycock body surface area ratio (BSAR), and body mass index ratio (BMIR). Multivariate Cox regression modeling was used to evaluate the risk of graft failure at 1-year. <h3>Results</h3> The bottom two DRWR quintiles were associated with higher risk compared to the middle DRWR quintile (Q1: 1.86 HR, p=0.002; Q2: 1.98, p=0.0004) (Table 1). The bottom two BSAR quintiles were also associated with higher risk compared to the middle BSAR quintile but to a lesser degree than DRWR (Q1: HR=1.74, p=0.005; Q2: HR=1.75, p=0.004). None of the DRHR quintiles or BMIR quintiles were associated with increased risk of 1-year graft failure compared to the middle quintile (Table 1). Ischemic time, retransplantation, ECMO at transplantation, and serum bilirubin were significant covariates associated with an increased risk of 1-year graft failure in each multivariate model. Later transplantation year was associated with lower risk of graft failure in each multivariate model. Serum creatinine, donor age, and recipient age were not associated with risk of graft failure in multivariate analysis. <h3>Conclusion</h3> Undersizing by DRWR or BSAR is associated with increased risk of graft failure in infant heart transplantation. Size mismatch by DRHR or BMIR is not predictive of graft failure when compared to modest oversizing (i.e., the middle quintile). Further investigation is needed to improve size-matching in infant heart transplantation.