The challenge of endomyocardial biopsy interpretation in assessing cardiac allograft rejection.

The endomyocardial biopsy has long been the preferred technique for monitoring the rejection status of the cardiac allograft. During the past year, published reports have addressed important issues concerning the endomyocardial biopsy, including the reliability of the International Society for Heart and Lung Transplantation grading system; problem areas in posttransplantation biopsy interpretation, including grade 2 rejection and myocyte injury, Quilty lesions, and ischemic injury; the natural history of grade 2 rejection; the necessity of surveillance biopsies late in the posttransplantation course; and the efficacy of numerous noninvasive techniques in diagnosing or predicting rejection. No technique developed to date has been shown to have the sensitivity or specificity needed to replace the endomyocardial biopsy as a diagnostic tool. In addition, studies of endomyocardial biopsy specimens have furthered our understanding of the pathobiology of rejection and other transplant-related conditions.