Relationship of ventricular assist device support duration with pediatric heart transplant outcomes

Background: There is wide variability in the timing of heart transplant (HTx) after pediatric VAD implant. While some centers wait months before listing for HTx, others accept donor heart offers within days of VAD surgery. We sought to determine if HTx within 30 days versus ≥ 30 after VAD impacts post-HTx outcomes.

Methods: Children on VAD pre-HTx were extracted from the Pediatric Heart Transplant Study database. The primary endpoints were post-HTx length of hospital stay (LOS) and one-year survival. Confounding was addressed by propensity score weighting using inverse probability of treatment. Propensity scores were calculated based on age, blood type, primary cardiac diagnosis, decade, VAD type, and allosensitization status.

Results: A total of 1064 children underwent VAD prior to HTx between 2000 to 2018. Most underwent HTx ≥ 30 days post-VAD (70%). Infants made up 22% of both groups. Patients ≥ 12 years old were 42% of the < 30 days group and children 1 to 11 years comprised 47% of the ≥ 30 days group (p < 0.001). There was no difference in the prevalence of congenital heart disease vs. cardiomyopathy (p = 0.8) or high allosensitization status (p = 0.9) between groups. Post-HTx LOS was similar between groups (p = 0.11). One-year survival was lower in the < 30 days group (adjusted mortality HR 1.76, 95% CI 1.11-2.78, p = 0.016).

Conclusions: A longer duration of VAD support prior to HTx is associated with a one-year survival benefit in children, although questions of patient complexity, post-VAD complications and the impact on causality remain. Additional studies using linked databases to understand these factors will be needed to fully assess the optimal timing for post-VAD HTx.