Nonlinear characterization of ECGs in patients with Chagas’ disease*

According to the World-Wide Organization of the Health, the number of people infected with the Tripanosoma Cruzi is considered between 6 and 8 million, causal agent of the Chagas’ disease , and in 550000 the people are expected to be exposed to the affectation risk. When concluding in 1983 a longitudinal epidemiologist study in patients with the disease evaluated 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 (HRV) in patients with the Chagas’ disease, show alterations in the spectral indices of the HRV. A nonlinear modeling technique allows the definition of early risk markers in patients with Chagas’s disease and without any evidence of cardiac involvement evaluated by standard diagnostic test (CH1). We analyze ECGs by Holter recordings in patients with ECG alterations (CH2), patients without ECG alterations (CH1) who had positive serological findings for Chagas’ disease and healthy (Control) matched for sex and age. Two ECGs were digitized for each volunteer, one begins at supine position and the other at orthostatic position. The technique applied is based upon quantitative comparison of the evolution from similar ECGs Sub segments, and a measure of the predictability decay rate were calculated for each register. We did find significant differences among Control and CH2 during supine and also standing with high sensibility and specificity in the early detection of cardiac involvement. It is suggested that these alterations are very early autonomic disturbances in patients without ECG alterations (CH1) that could be useful to enhance risk stratification.