RESUMO
Successive periods of reactivation of Trypanosoma cruzi in the myocardium may contribute to chronic, progressive myocardial damage and fibrosis, indicating that viable parasites are still present in the host, although the infection may remain quiescent or inapparent. Identifying the presence of active infection as well as the intensity of the inflammatory process can lead to the administration of more effective chemotherapeutic agents to exterminate the parasite. We investigated the use of Tc-99m-mononuclear leukocytes as a complementary tool for the diagnosis of active chagasic myocarditis. Using the stannous chloride labeling method, previously reported by us, 22 patients underwent Tc-99m-leukocyte scintigraphy. Planar images were obtained after 30 minutes, 3 and 24 hours of endovenous administration of approximately 444MBq (12 mCi) of the labeled cells. There was abnormal cardiac uptake in 3 of the 22 patients. These findings suggest the presence of markedly Chagas' disease activity with important clinical implications.