title: Effect of exercise training in patients with heart failure: a pilot study on autonomic balance assessed by heart rate variability.
abstract: BACKGROUND
  Heart rate variability (HRV) is decreased in patients with congestive heart failure (CHF) and is a prognostic marker in this disease. Exercise training is now regarded as an important part of the treatment of patients with CHF, but the effect on HRV and the association between this effect and the effect on neurohormones are not well assessed.
  
  
  METHODS
  Heart rate recording was performed in 12 patients with CHF (mean age 67+/-8 years) with CHF NYHA functional class III, before and after 12 weeks of exercise training. The association with exercise capacity and serum levels of atrial natriuretic peptide was assessed. We also evaluated the correlation between HRV and survival at follow-up 87 months later.
  
  
  RESULTS
  At baseline there was a significant correlation between mean heart rate and work performed during max cycle test (r=0.650, P=0.022) and the HRV parameter standard deviation normal to normal (SDNN) (r=0.678, P=0.015). After exercise training there was a significant increase in work performed (30.3+/-14.2 versus 38.1+/-14.1 kJ), 6-min walk test (502+/-88 versus 552+/-59 m, P=0.006) and SDNN (117.3+/-40.7 versus 128.6+/-42.3 ms, P=0.028). At 87 months of follow-up, there was a borderline significant difference between survivors and non-survivors. Only the survivors had a significant increase in SDNN after exercise training.
  
  
  CONCLUSIONS
  This pilot study demonstrates an improvement with regard to parameters for HRV after exercise training in patients with CHF. The study suggests that the positive effect of exercise training in patients with CHF involves an attenuation of the reduced HRV response, and that this improvement might have prognostic significance.
authors.affiliation: University of Bergen, Cardiology Division, Central Hospital in Rogaland, Stavanger, Norway. al-i-lar@online.no
authors.forename: Alf Inge
authors.initials: AI
authors.lastname: Larsen
authors.forename: Knut
authors.initials: K
authors.lastname: Gjesdal
authors.forename: Christian
authors.initials: C
authors.lastname: Hall
authors.forename: Pål
authors.initials: P
authors.lastname: Aukrust
authors.forename: Torbjørn
authors.initials: T
authors.lastname: Aarsland
authors.forename: Kenneth
authors.initials: K
authors.lastname: Dickstein
mesh_terms: D000368:Aged; D009320:Atrial Natriuretic Factor / Q000097:blood; D001341:Autonomic Nervous System / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D006333:Heart Failure / Q000097:blood / Q000503:physiopathology* / Q000534:rehabilitation*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011498:Protein Precursors / Q000097:blood; D012146:Rest / Q000502:physiology
chemical_list: C099254:N-terminal proatrial natriuretic peptide; D011498:Protein Precursors; D009320:Atrial Natriuretic Factor