Pathologic Analysis of Endomyocardial Biopsies in Heart Transplantation

ABSTRACT

Endomyocardial biopsy (EMB) is a valuable diagnostic procedure for the surveillance of cardiac allograft rejection. Interpretation of individual cases is still problematic due to variations of findings for grading of rejection and other associated lesions. We reevaluated an experience on endomyocardial biopsies to develop better diagnostic criteria for rejection and other complications. Immunohistochemical studies against cytokines were performed to assess the usefulness of the method for the diagnosis or researches. A total of 249 EMBs taken from 33 cardiac allograft recipients were reviewed. There were 25 males and 8 females. Dilated cardiomyopathy was present (24 cases) and valvular heart disease (4 cases), restrictive cardiomyopathy (3 cases) were also common conditions. We applied the grading system of the International Society for Heart Transplantation (ISHT) for the assessment of acute cellular rejection. Grades of 0, 1A, 1B, 2, 3A and 3B were 39.0%, 28.1%, 11.2%, 11.5%, 12.4% and 1.6% respectively, but 3.2% were inadequate. Thirty five episodes of grade 3A or 3B were present in 17 patients. The response to therapy was assessed using a next follow up biopsy, which revealed resolving or resolved rejection in 85% of patients. The intensity of immunohistochemical stains for IL-6 and TNF-alpha was increased in proportion to the histologic grade but Quilty lesion and cardiomyopathy also showed a positive reaction. The other pathologic findings were ischemic change, previous biopsy site, interstitial edema and fibrosis, and Quilty lesion. These findings showed usefulness of endomyocardial biopsy not only for the evaluation of cardiac allograft rejection but also for the diagnosis of associated cardiac lesions. Immunohistochemical study of the cytokines was related to the degree of inflammation rather than degree of rejection.