Objectives: This study aimed to compare indium-111 (111In)-monoclonal antimyosin antibody uptake in patients with dilated cardiomyopathy before heart transplantation with the histologic findings in the explanted hearts.
Background: A high prevalence of 111In-monoclonal antimyosin antibody uptake has been described in patients with dilated cardiomyopathy, suggesting the presence of active, ongoing myocyte damage; however, no correlation between monoclonal antimyosin antibodies and histologic findings is available in these patients.
Methods: A consecutive series of 21 patients with dilated cardiomyopathy awaiting heart transplantation were studied with monoclonal antimyosin antibodies before the operation, and the results were compared with the histologic analysis of the explanted hearts. The interval between monoclonal antimyosin antibody studies and transplantation was 1 to 90 days (mean 58 +/- 31).
Results: Using a semiquantitative method (heart/lung ratio), monoclonal antimyosin antibody uptake was present in 15 (71%) of 21 patients, but active myocarditis in the explanted hearts was detected in only 7. In 11 patients, intense monoclonal antimyosin antibody uptake coexisting with absent myocyte damage or cellular infiltration of explanted hearts was noted. One patient who showed preoperative monoclonal antimyosin antibody uptake underwent transplantation 11 h later, and ex vivo diffuse myocardial antimyosin uptake was detected, but active myocarditis was seen only at cardiectomy in only a small area of the heart; the rest of the myocardium showed no signs of myocyte damage.
Conclusions: In dilated cardiomyopathy, monoclonal antimyosin antibody uptake cannot be equated with the presence of an inflammatory response detected in the myocardium of the explanted heart.