Rejection! Or is it? Correlation among molecular microscope diagnostic system, histopathology and clinical judgement following heart transplantation.

PURPOSE: Little is known about clinical decision making among discordant findings concerning for rejection with endomyocardial biopsy (EMBx) and Molecular Microscope Diagnostic System (MMDx) in patients following heart transplantation. METHODS: Two hundred and twenty-eight corresponding EMBx and MMDx specimens from 135 adult heart transplant patients were retrospectively reviewed. Rejection was classified as t-cell mediated rejection ≥2R and/or antibody mediated rejection ≥1. Clinical decision making among concordant and discordant cases of EMBx and MMDx results were reviewed. RESULTS: Patient characteristics were comparable between concordant and discordant patient groups (median age 60 yrs., 76% male, and 71% White). A total of 167/228 specimens (73%) were concordant for no rejection with 98% agreement in clinical decision making and 25/228 (11%) concordant for rejection with 64% agreement in clinical decision making. Among the 36/228 (16%) discordant samples, clinical decision-making agreed on treatment for rejection in five of the MMDx samples and three of the EMBx samples. CONCLUSIONS: MMDx can be an additional tool to diagnose rejection not detected by the traditional EMBx and influence clinical decision making in guiding appropriate treatment. Ongoing investigation into the clinical utility of MMDx is warranted to determine the significance of discordant findings among diagnostic modalities when assessing for rejection.