EVALUATION OF BIOPSY CLASSIFICATION FOR REJECTION - RELATION TO DETECTION OF MYOCARDIAL DAMAGE BY MONOCLONAL ANTIMYOSIN ANTIBODY IMAGING

Objectives. This study sought to compare the histologic grades of reje ction in endomyocardial biopsy specimens with the global estimate of m yocardial transplant related cardiac damage detected by myocardial upt ake of monoclonal antimyosin antibodies. Background. The diagnosis and treatment of acute cardiac allograft rejection is based on the interp retation of endomyocardial biopsies. Because allograft rejection is a multifocal process and biopsy is obtained from a small area of the rig ht ventricle, sampling error may occur. Global assessment of myocardia l damage associated with graft rejection is now possible with the use of antimyosin scintigraphy, The present study was undertaken to compar e the histologic grades of rejection in endomyocardial biopsy specimen s with the global assessment of transplant-related myocardial damage d etected by antimyosin scintigraphy.Methods. Biopsies (n = 395) from 11 2 patients were independently interpreted by three pathologists in a b linded manner according to the original Stanford four-grade (normal, m ild, moderate and severe) and the current International Society of Hea rt and Lung Transplantation (ISHLT) seven-grade (0, 1A, 1B, 2, 3A, 3B and 4) classifications, The results were correlated with 395 antimyosi n studies performed at the time of the biopsies. The heart/lung ratio of antimyosin antibody uptake was used to assess the severity of myoca rdial damage. Results. In the Stanford biopsy grade classification, si gnificantly higher antimyosin uptake, indicating increasing degrees of myocardial damage, were associated with normal (1.78 +/- 0.26), mild (1.88 +/- 0.31) and moderate (1.95 +/- 0.38) biopsy classifications fo r rejection (p < 0.01), In the ISHLT classification, significant diffe rences were detected only for antimyosin uptake associated with grades 0 (1.77 +/- 0.26) and 3A (1.98 +/- 0.39) but not for intermediate sco res (1A, 1B and 2), In view of the similar intensity of antibody uptak e among the various grades, ISHLT biopsy scores were regrouped: normal biopsies in grade A; 1A and 1B as grade B; and 2 and 3A as grade C, A ntimyosin uptake in grades A, B and C was 1.78 +/- 0.26, 1.88 +/- 0.31 , 1.95 +/- 0.38, respectively (p < 0.01). Conclusions. The current ISH LT seven-grade scoring system does not reflect the progressive severit y of myocardial damage associated with heart transplant rejection. Bec ause myocardial damage constitutes the basis of treatment for allograf t rejection, there is a need to reevaluate the ISHLT grading system, g iven its importance for multicenter trials. (C) 1998 by the American C ollege of Cardiology.