De novo donor-specific HLA antibodies in heart transplantation: Do transient de novo DSA confer the same risk as persistent de novo DSA?

BACKGROUND: It is estimated that 25%-35% of heart transplant recipients develop de novo donor-specific antibodies (dnDSA). One factor that appears to play a role in clinical outcomes is DSA persistence. The objective of this study was to determine the incidence of transient and persistent dnDSA in a Canadian heart transplant population and to evaluate their impact on coronary allograft vasculopathy (CAV), graft function, and mortality. METHODS: A retrospective study of consecutive adult and transitioned pediatric heart transplant recipients (2008-2015) in Toronto was performed. Clinical demographics were collected prospectively. HLA antibody testing was performed using Luminex single antigen assays. In statistical analysis, dnDSA was modeled as a time dependent covariate. RESULTS: During a median follow-up of 4.1 years, dnDSA were detected in 42 (23%) with a median time to detection of 329 days (156-740); 27 (64%) developed persistent dnDSA. Persistent dnDSA conferred an increased risk of death with a HR 4.0 (95%CI 1.4-12.1) when adjusted recipient age, CAV, and cytomegalovirus status. CONCLUSIONS: Transient dnDSA were not associated with adverse outcomes after heart transplantation. This suggests that transient dnDSA may not require enhanced immunosuppression, increased HLA antibody monitoring, or additional physiological assessment. By knowing the transient dnDSA status, clinicians may minimize both recipient morbidity and cost without increasing harm.