Natural history of chronic Chagas' heart disease: prognosis factors.

Chronic Chagas' disease shows several progression modes. Usually, the different clinical syndromes manifest themselves together, however, isolated forms can occur. Cardiac arrhythmias, which are very frequent, are present in about 50% of patients. The cardiac damage manifests itself later, with the emergence of heart failure. Thromboembolism can occur in both pulmonary and systemic circulation. Pulmonary embolism is the most frequent, appearing in more advanced phases of heart disease. Sudden death is the fatal outcome of these patients. It predominates in males and generally occurs in a disease stage when patients have their highest productivity. The presence of serious ventricular arrhythmias, conduction disturbances in the electrocardiogram, and heart failure, provide an unfavorable prognosis.