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.

Conclusion

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.