RESUMO
BACKGROUND: Heart rate recovery (HRR) is a marker of vagal tone that is associated with survival, but little is known about the effects of exercise training on HRR in patients with heart failure (HF). METHODS: Twenty-four patients with HF were randomized to a 2-month residential rehabilitation program or to usual care. Symptom-limited exercise testing was performed at baseline and at discharge from the program. Heart rate recovery was expressed as the decline in heart rate from peak exercise through 6 minutes into recovery. In addition, HRR recovery curves were normalized to a range of 1 at peak heart rate and 0 at 6 minutes and adjusted for differences in heart rate reserve, facilitating the comparison of recovery curve shapes between groups. RESULTS: Mean peak oxygen uptake and oxygen uptake at the lactate threshold increased 26% (P < .05) and 39% (P < .001), respectively, in the exercise group, whereas neither of these responses changed significantly among controls. Heart rate recovery was significantly more rapid in the exercise group after training (main effect 12.6 vs 2.6 beat/min in the trained and control groups, respectively, P = .005). The normalized curves showed that the largest improvement in recovery curve shape occurred in the exercise group, but most of the HRR improvement was accounted for by a widening of the difference between peak and resting heart rate. CONCLUSION: Exercise training results in a faster HRR in patients with HF. Heart rate recovery, as a simple marker of autonomic function, is an easily acquired response that may be useful for evaluating patient outcomes in cardiac rehabilitation.
