 3. Se supplementation prevented the myocardial lesions at the acute phase in mice. From these findings and considering that Se supplementation was able to prevent Keshan cardiopathy, to revert electrocardiographic and echocardiographic alterations in patients nourished by parenteral route, and reduced re-infarction and cardiac deaths from acute myocardial infarction; the investigators purpose to investigate if Se treatment via oral route, is able to impair the progress of heart dysfunction in chagasic patients expressed by the study of progression rate and by the comparison of the means of ventricular ejection fraction. 