ACTIVE MYOCARDIAL DAMAGE WITHOUT ATTENDING INFLAMMATORY RESPONSE IN DILATED CARDIOMYOPATHY

Objectives. This study aimed to compare indium-111 (In-111)-monoclonal antimyosin antibody uptake in patients with dilated cardiomyopathy be fore heart transplantation with the histologic findings in the explant ed hearts. Background. A high prevalence of In-111-monoclonal antimyos in antibody uptake has been described in patients with dilated cardiom yopathy, suggesting the presence of active, ongoing myocyte damage; ho wever, no correlation between monoclonal antimyosin antibodies and his tologic findings is available in these patients. Methods. A consecutiv e series of 21 patients with dilated cardiomyopathy awaiting heart tra nsplantation were studied with monoclonal antimyosin antibodies before the operation, and the results were compared with the histologic anal ysis of the explanted hearts. The interval between monoclonal antimyos in antibody studies and transplantation was 1 to 90 days (mean 58 +/- 31). Results. Using a semiquantitative method (heart/lung ratio), mono clonal antimyosin antibody uptake was present in 15 (71%) of 21 patien ts, but active myocarditis in the explanted hearts was detected in onl y 7. In 11 patients, intense monoclonal antimyosin antibody uptake coe xisting with absent myocyte damage or cellular infiltration of explant ed hearts was noted. One patient who showed preoperative monoclonal an timyosin antibody uptake underwent transplantation 11 h later, and ex vivo diffuse myocardial antimyosin uptake was detected, but active myo carditis was seen only at cardiectomy in only a small area of the hear t; the rest of the myocardium showed no signs of myocyte damage. Concl usions. In dilated cardiomyopathy, monoclonal antimyosin antibody upta ke cannot be equated with the presence of an inflammatory response det ected in the myocardium of the explanted heart.