The usefulness of the application of nonlinear dynamics in the analysis ofelectrocardiograms in Chagas' disease patients

Introduction and objectives. The application of nonlinear techniques allows the definition of early risk markers in patients with Chagas infection and without any evidence of cardiac involvement evaluated by standard diagnost ic test. Nonlinear modeling techniques have proved to be effective in cardi ac rhythm analysis, thereby justifying its use in Chagas' disease. Patients and method. The routine noninvasive test and heart rate variabilit y analysis were performed in Chagas' disease patients and in a group of hea lthy subjects. In a second phase we used nonlinear analysis in the evaluati on of patients with Chagas infection and no evidence of heart disease, Chag asic patients with minimal electrocardiographic abnormalities and healthy c ontrols. Results. Twenty-four-hour electrocardiographic ambulatory monitoring and he art rate variability allowed us to establish differences between the health y subjects and patients with Chagas infection without evidence of cardiac d isease (p < 0.05 and p < 0.005). In sharp contrast nonlinear analysis chara cterized 4 subgroups in Chagasic patients without cardiac involvement (sens itivity and specificity of 100%). Conclusions. Our findings suggest that nonlinear modeling techniques have a high sensitivity and specificity in the early detection of cardiac involve ment and very early autonomic disturbance. We recommend that these techniqu es be applied to patients with high risk of cardiac disease other than Chag asic myocarditis. Our findings should be corroborated with studies in large r populations. We are currently developing a prospective study to this end.