Allosensitization status predicts excess mortality in pediatric congenital heart disease transplant recipients in the current era: An analysis of the United Network for Organ Sharing database.

Background: Patients with congenital heart disease are at high risk of allosensitization and as such may be at risk for inferior outcomes following heart transplantation. Methods: The United Network for Organ Sharing database was studied for patients <18 years with congenital heart disease undergoing heart transplantation from April 2015 to December 2020. Patients were grouped into 3 categories of allosensitization status based on % calculated panel reactive antibody at transplant: non- (<10%), moderately- (10%-<80%), and highly sensitized (≥80%). Primary outcome measures were 1-year patient and graft survival. Multivariable analysis controlled for differences in preoperative clinical characteristics among categories. Results: During the study period, 1,086 patients with congenital heart disease underwent transplant at a median of 3 years of age. Nonsensitized patients comprised 70%; 22% were moderately sensitized and 9% were highly sensitized. Unadjusted 1-year mortality was 25% in the highly sensitized and 8.7% in the nonsensitized group (p < 0.001). After adjustment, highly sensitized patients were >3 times more likely to die within the first year than nonsensitized patients (HR 3.44, p < 0.001). The relationship between calculated panel reactive antibody and crossmatch result was assessed using multivariable regression. Regardless of crossmatch result, highly sensitized patients had an increased risk of 1-year mortality (HR 3.4, p < 0.001) and graft failure (HR 3.32, p < 0.001) compared to nonsensitized and moderately sensitized patients. Conclusions: Highly sensitized patients with congenital heart disease undergoing heart transplantation in the current era experience 25% 1-year mortality. The magnitude of sensitization predicts adverse outcomes.