Variabilidade da Frequência Cardíaca em idosos de um município da Amazônia brasileira com ênfase na Síndrome da Fragilidade

Abstract

Background: Heart rate variability (HRV), a method of indirect assessment of the autonomic nervous system, has been a field of growing interest in the scientific community due to its relationship as a predictor of several clinical conditions. Some studies describe a decrease in HRV in Frailty, an adverse condition characterized by a higher loss of biological reserves than expected in the normal aging process, and HRV is a possible predictor of frailty. There is also evidence that HRV rates are modified in the elderly compared to younger adults and also differ between sexes. Objectives: Investigating the association of HRV indices in relation to the fragility phenotype, age and sex in a sample composed of elderly people from a municipality of the Brazilian Amazon. Methods: Initially, participants were interviewed to obtain the sociodemographic profile and health history. In a second moment, they were submitted to HRV assessment at rest for 10 minutes. The elderly were also evaluated for the fragility phenotype according to the criteria of Fried et al. Subsequently, the data were analyzed in the time domain, frequency domain and nonlinear analysis. HRV variables were compared between groups by Frailty Phenotype, age and sex. Results: No association was found between age and HRV in this sample, but differences were found between sexes in frequency domain components (high frequency component - (HF)) and nonlinear analysis (Sample Entropy), with higher values among women. Regarding the Frailty Phenotype, no association was found with HRV in the domains analyzed. Conclusion: The findings reinforce the evidence that differences in HRV only occur when comparing older adults with younger adults, but not among elderly people. The higher values of HF and Sample Entropy found among women may suggest that differences in HRV between sexes remain even among the elderly. In the present study, HRV was not a good predictor for Frailty.