 Currently, experimental and clinical trials concerning Se supplementation have been performed; however, to date, there is no trial regarding the use of this micronutrient as a treatment to protect cardiac function in chagasic patients with cardiopathy. The present clinical trial aims to study the effect of Se intervention on the progression rate of the cardiopathy in patients with mild or moderate HD LVEF between 35 and 45 in order to validate this new strategy of treatment. The HD will be expressed by the progression rate and by the comparison of means of the LVEF. In this context we will test the hypothesis that Se treatment is able to interfere with the progression of cardiac dysfunction in chronic chagasic patients. We expect the impediment of the progression of ventricular dysfunction in patients with mild HD, and the improvement of cardiac function in patients with moderate HD in the group of patients receiving Se therapy. This is the first clinical trial concerning this specific group of cardiac chagasic patients with mild or moderate HD. 