According to the World wide Organization of the Health, the number of people infected with the Tri- panosoma Cruzi is considered between 16 and 18 million, causal agent of the Chagas' disease, and in 100 million the people exposed to the affectation risk. When concluding in 1983 a study longitudinal epidemiologist in patients with the disease evaluated [2, 3] every 3 years, the cardiac affectation: chronic Chagasic myocarditis (MCHC) increased from a 17% at the beginning of the study to a 49, 4% after 15 years. Previous studies of the variability of cardiac frequency in patients with the Chagas' disease[4, 5], show alterations in the spectral indices of the HRV. We analyze the 24-hour heart rate by Holter recordings in 62 patients with ECG alterations (CH2), 32 patients without ECG alterations (CH1) who had positive serological findings for disease of Chagas' and 36 healthy subjects (Control) matched for sex and age. We find a orthogonal base that is able to discriminate the groups from circadian profiles, Control and CH2, and stratify the groups CH1.