Association of Clinical Rejection Versus Rejection on Protocol Biopsy With Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients

Abstract

Two or more early rejections (<1 y) or any late acute rejection (>1 y) have been associated with coronary artery vasculopathy (CAV) in pediatric heart transplant (HT) recipients. We hypothesized that clinical rejection defined by concurrent new-onset heart failure or left ventricular systolic dysfunction is more strongly associated with future CAV than rejection diagnosed on protocol biopsy. We identified all subjects <21 years old who received first HT at Boston Children's Hospital during 1986-2015 with at least 1 post-HT coronary angiogram. CAV was diagnosed using 2010 International Society for Heart and Lung Transplantation guidelines. Time to CAV diagnosis was assessed using a Cox model with occurrence of clinical rejection analyzed as a time-varying covariate. Of 228 study subjects, 106 remained rejection-free, 77 had rejection diagnosed only on protocol biopsy (≥2R cellular or antibody-mediated), and 45 had a clinical rejection. Subjects with rejection diagnosed only on protocol biopsy were not at higher risk of CAV (hazard ratio [HR] 1.09, 95% confidence interval [CI]: 0.54-2.09). In contrast, clinical rejection was significantly associated with risk of CAV (HR 4.84, 95% CI: 2.99-7.83). Late rejection was associated with a higher risk of CAV (HR 4.27, 95% CI: 2.42-7.51) if it was clinical rejection but not if it was diagnosed on protocol biopsy (HR 0.83, 95% CI: 0.51-1.37). Clinical rejection poses a far greater risk for future CAV than rejection on protocol biopsy in pediatric HT recipients. Preventing CAV should therefore become the focus of medical management after initial treatment and resolution of clinical rejection.