Semilunar Valve Function After Rejection in Heart Transplant Recipients: Implications for Partial Heart Transplantation.

BACKGROUND

Partial heart transplantation (PHT) is a promising procedure for pediatric patients with irreparable semilunar valve disease. Current immunosuppression regimens mirror orthotopic heart transplant (OHT) protocols. However, semilunar valves may have immune privilege, making true immunosuppressive requirements unclear. This study examines the effect of rejection on semilunar valves in OHT to inform immunosuppression strategies for PHT.

METHODS

We conducted a single-center retrospective case-control study of pediatric OHT recipients from 2008 to 2023. Patients were grouped by the presence or absence of rejection episodes, with further stratification by rejection severity. Semilunar valve function was assessed via echocardiography at baseline, during, and after rejection episodes. Subgroup analysis was performed based on rejection severity and age at transplant (< 1 year of age).

RESULTS

Of 113 eligible OHT recipients, 57 had ≥ 1 rejection episodes (32 high-grade). Baseline valve function was comparable between rejection and non-rejection groups. After a 3.8-year median follow-up, there were no significant differences in aortic or pulmonary valve gradients or in the prevalence of clinically significant regurgitation between groups. Paired analysis during rejection demonstrated no change in valve function compared to pre-rejection assessment. Similar findings were observed in infants transplanted < 1 year of age.

CONCLUSIONS

Over a median follow up of nearly 4 years, semilunar valve function in pediatric OHT recipients remained clinically unaffected by rejection, even in high-grade cases and among younger patients. These findings support the hypothesis of semilunar valve immune privilege and suggest that intensive immunosuppression may not be necessary to preserve valve function after PHT.