Revealing alterations in heart rate fluctuations during the progression of Chagas disease

Abstract

Introduction: The heart rate variability (HRV) continually evolves throughout life, reflecting modifications in the architecture of the sinoatrial node (SAN) and in the regulation of heart rate by the autonomic nervous system (ANS). Both can be considerably affected by Chagas disease, causing important changes in the complex nature of HRV. We aim to evaluate the ability of an index based on the false nearest neighbors method (FN10) to reflect these changes during disease progression.

Methods: We perform a retrospective, descriptive, and cross-sectional study analyzing HRV time series of participants with Chagas disease. We determine the dependence of FN10 on age and sex in a healthy population, and then evaluate FN10 in individuals with Chagas disease.

Results and discussion: In the healthy population, FN10 has a scaling behavior with age, which is independent of sex. In Chagas disease, some individuals show FN10 values significantly above those seen in the healthy population. We relate the findings to the pathophysiological mechanisms that determine the progression of the disease. The results indicate that FN10 may be a candidate prognostic biomarker for heart disease.

Keywords: Chagas disease; autonomic nervous system; fibrosis; heart rate variability; sinoatrial node.

Figure 1

Some curves of false nearest neighbors (FNN) as a function of the spatial dimension (d) representative of the population of healthy individuals (A) and individuals with Chagas disease (B).

Figure 2

Dependence of FN10 on age expressed in years for the healthy population. Dotted lines define the boundaries of the prediction intervals with 95% confidence.

Figure 3

Dependence of FN10 on age expressed in years for individuals with CD. The lines represent the behavior determined in Figure 2 for healthy individuals. Data from the three groups are shown: GA (circles), GB (triangles), and GC (squares).

Figure 4

Percentage of FN10⁺ CD individuals for each group. There is a small percentage of false positives in the control group (CG).