Dysautonomia Evaluation by Holter in Chagas Heart Disease

ABSTRACT

Abstract Background Sudden cardiac death is the main lethal mechanism associated with Chagas cardiomyopathy. Studies suggest that dysautonomia may represent a relevant, intense, independent, and early phenomenon in the natural history of the disease, even when ventricular systolic function is preserved, and may also be the mechanism that triggers malignant ventricular arrhythmias. Objective To evaluate the degree of dysautonomia and its possible association with ventricular arrhythmias in patients with Chagas cardiomyopathy, according to different categories of mortality risk, as defined by the score proposed by Rassi, used as a surrogate outcome for death. Methods A cross-sectional study involving 43 patients with Chagas cardiomyopathy stratified into risk categories based on the Rassi score, with 23 being classified as low risk and 20 as intermediate-to-high risk. Heart rate variability (HRV) was assessed using Holter monitoring for long-term recordings of 24 hours (time domain) and for short-term recordings of 5 minutes (frequency domain) at rest and after autonomic tests deep breathing and Valsalva maneuver. The HRV variables were compared between the groups using the Student's t-test and α=0.05. Results Comparison of the results between the risk stratification groups showed no differences in HRV indexes, either in the time or frequency domain. However, results showed a significant increase in the number of arrhythmias as a function of increased risk (p=0.02). Conclusion There was no association between the degree of dysautonomia, evaluated by Holter monitoring, and the categories of mortality risk, despite a direct association between the rate of arrhythmias and the higher risk group.