Myocardiocyte apoptosis in heart failure in chronic Chagas' disease.

Chagas' disease is caused by the parasite Trypanosoma cruzi. The disease affects 16-18 million patients in South America and heart involvement is the major cause of morbidity and mortality of the disease. The myocarditis observed during the chronic phase affects patients independently of the clinical manifestation, although patients with heart failure present an intense degree of myocarditis and fibrosis. To address the pathogenesis of heart failure in Chagas' disease, we investigated the role of myocardial cell loss by apoptosis in patients in the chronic phase of Chagas' disease. Apoptosis was also evaluated in inflammatory cells. Twenty-two specimens of the left ventricle were obtained during autopsies. Eleven samples from patients with heart failure and equal number from patients without heart failure. The material was analyzed by TUNEL methods to identify early apoptotic events and fibrosis was evaluated on HE-stained slides. In patients with heart failure, the extent of fibrosis and the number of apoptotic myocardial and inflammatory cells were significantly higher than in specimens obtained from patients without heart failure. These results suggest that myocardial cell loss by apoptosis and fibrosis contribute to heart failure in the chronic phase of Chagas' disease.