title: Effects of exercise training on heart rate variability in Chagas heart disease.
abstract: BACKGROUND
  Heart rate variability (HRV) is a marker of autonomic dysfunction severity. The effects of physical training on HRV indexes in Chagas heart disease (CHD) are not well established.
  
  
  OBJECTIVE
  To evaluate the changes in HRV indexes in response to physical training in CHD.
  
  
  METHODS
  Patients with CHD and left ventricular (LV) dysfunction, physically inactive, were randomized either to the intervention (IG, N = 18) or control group (CG, N = 19). The IG participated in a 12-week exercise program consisting of 3 sessions/week.
  
  
  RESULTS
  Mean age was 49.5 ± 8 years, 59% males, mean LVEF was 36.3 ± 7.8%. Baseline HRV indexes were similar between groups. From baseline to follow-up, total power (TP): 1653 (IQ 625 - 3418) to 2794 (1617 - 4452) ms, p = 0.02) and very low frequency power: 586 (290 - 1565) to 815 (610 - 1425) ms, p = 0.047) increased in the IG, but not in the CG. The delta (post - pre) HRV indexes were similar: SDNN 11.5 ± 30.0 vs. 3.7 ± 25.1 ms. p = 0.10; rMSSD 2 (6 - 17) vs. 1 (21 - 9) ms. p = 0.43; TP 943 (731 - 3130) vs. 1780 (921 - 2743) Hz. p = 0.46; low frequency power (LFP) 1.0 (150 - 197) vs. 60 (111 - 146) Hz. p = 0.85; except for high frequency power, which tended to increase in the IG: 42 (133 - 92) vs. 79 (61 - 328) Hz. p = 0.08).
  
  
  CONCLUSIONS
  In the studied population, the variation of HRV indexes was similar between the active and inactive groups. Clinical improvement with physical activity seems to be independent from autonomic dysfunction markers in CHD.
authors.affiliation: Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Bruno Ramos
authors.initials: BR
authors.lastname: Nascimento
authors.affiliation: Faculdade de Medicina, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Márcia Maria Oliveira
authors.initials: MM
authors.lastname: Lima
authors.affiliation: Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Maria do Carmo Pereira
authors.initials: Mdo C
authors.lastname: Nunes
authors.affiliation: Serviço de Cardiologia e Cirurgia Cardiovascular, Hospital das Clínicas, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Maria Clara Noman de
authors.initials: MC
authors.lastname: Alencar
authors.affiliation: Faculdade de Medicina, UFMG, Belo Horizonte, MG, Brazil.
authors.forename: Henrique Silveira
authors.initials: HS
authors.lastname: Costa
authors.affiliation: Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Marcelo Martins
authors.initials: MM
authors.lastname: Pinto Filho
authors.affiliation: Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Vitor Emanuel Serafim
authors.initials: VE
authors.lastname: Cota
authors.affiliation: Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Manoel Otávio da Costa
authors.initials: MO
authors.lastname: Rocha
authors.affiliation: Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Antonio Luiz Pinho
authors.initials: AL
authors.lastname: Ribeiro
mesh_terms: D000328:Adult; D014355:Chagas Disease / Q000503:physiopathology / Q000628:therapy*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy*
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