Myocardial parasite persistence in chronic Chagasic patients

The persistence of Trypanosoma cruzi tissue forms was detected in the myoca rdium of seropositive individuals clinically diagnosed as chronic chagasic patients following endomyocardial biopsies (EMBs) processed by immunohistoc hemical (peroxidase-anti-peroxidase [PAP] staining) and molecular (polymera se chain reaction [PCR]) techniques. An indirect immunofluorescent techniqu e revealed antigenic deposits in the cardiac tissue in 24 (88.9%) of 27 pat ients. Persistent T. cruzi amastigotes were detected by PAP staining in the myocardium of 22 (84.6%) of 26 patients. This finding was confirmed with a PCR assay specific for T. cruzi in 21 (91.3%) of 23 biopsy specimens from the same patients. Statistical analysis revealed substantial agreement betw een PCR and PAP techniques (k = 0.68) and the PCR and any serologic test (k = 0.77). The histopathologic study of EMB specimens from these patients re vealed necrosis, inflammatory infiltrates, and fibrosis, and made it possib le to detect heart abnormalities not detected by electrocardiogram and/or c ineventriculogram. These indications of myocarditis were supported by the d etection of T. cruzi amastigotes by the PAP technique or its genome by PCR. They suggest that though the number of parasites is low in patients with c hronic Chagas' disease, their potential for heart damage may be comparable with those present during the acute phase. The urgent necessity for testing new drugs with long-term effects on T. cruzi is discussed in the context o f the present results.