The current standard for biopsy-based diagnoses of rejection of heart transplants is the ISHLT classification from 2004, which represents a widely-used international consensus, based on morphological criteria of the cellular infiltrate within the myocardial specimen system with certainties and some arbitrary and blurred parameters. Recent data-driven approaches using molecular and conventional technologies indicate that this system produces incorrect diagnoses with potential harm to patients due to inappropriate treatment. To address this unmet need and improve diagnostics in the area of organ transplantation, the Alberta Transplant Applied Genomics Centre (ATAGC, University of Alberta) has developed a new diagnostic system - the Molecular Microscope® Diagnostic System (MMDx) that interprets biopsies in terms of their molecular phenotype, and combines the molecular and histopathological features of transplant biopsies, plus clinical and laboratory parameters, to create the first Integrated Diagnostic System. The MMDx developed first in kidney transplant biopsies because phenotypes are well established, will now be adapted to heart transplant endomyocardial biopsies (EMBs). The present study will develop a Reference Set of EMB, adapt the MMDx system to assess and report EMBs; and validate and refine this system in 900 unselected prospectively collected for clinical indications and a standard of care EMBs from North American and European Centers. In addition to demonstrating the real-time feasibility and potential value of this System in patient care, the study will develop and optimize a transparent and user-friendly reporting format to communicate this information to clinicians and obtain detailed feedback to improve its utility. We refine now our MMDx system using a new type of analysis (see primary outcome) and the resulting MMDx report. Currently, INTERHEART recruited 1912 biopsies from 1279 patients.
