Identification of Heart Transplant Rejection Subtypes With Circulating MicroRNAs

BACKGROUND: Circulating microRNAs are promising biomarkers of acute cellular rejection (ACR) and antibody-mediated rejection (AMR) in heart transplantation. The study objective was to assess the characteristics and diagnostic performance of previously identified microRNAs and clinical rejection scores (CRS) in distinct blood samples obtained at the time of an endomyocardial biopsy (EMB). METHODS: In the 5-center, prospective, longitudinal cohort study, GRAfT (Genomic Research Alliance for Transplantation), microRNA sequencing was performed on blood samples. The previously identified microRNAs associated with ACR (n=12) and AMR (n=17) were used to fit a logistic regression model to the current cohort, and the scores were scaled from 0 to 100. Diagnostic performance of ACR and AMR microRNA panels was assessed by the area under the receiver-operating characteristic curve. An adjusted Cox proportional hazard model evaluated the effect of CRS on long-term outcomes. RESULTS: In 173 heart transplant recipients (29% female sex, 41% Black race, median follow-up 374 days after transplant), 922 blood samples were sequenced, 720 paired with EMB. Among 14 episodes of ACR, the median ACR CRS was 78 compared with 42 without ACR, P