Long-term effects of cardiac rehabilitation on end-exercise heart rate recovery after myocardial infarction

Background Heart rate recovery (HRR) is a marker of vagal tone that is a powerful predictor of mortality in patients with coronary artery disease. Design This study aims at evaluating the effects of long-term exercise training on HRR after acute myocardial infarction (AMI), in order to clarify whether prolonged exercise training could maintain a long-term improvement of HRR. Methods Forty-four patients after AMI were enrolled in a 3-month hospital-based exercise training programme. At the end, patients were subdivided into two groups: group A (n=22), patients discharged with a specific home-based exercise training programme and instructions for improving leisure-time physical activity; group B (n = 22), patients discharged with generic instructions to maintain physical activity. All patients underwent a cardiopulmonary exercise test before, at the end of 3 months exercise training and at 6 months follow-up. Results At the end of the hospital-based exercise training programme we observed an increase in peak oxygen consumption [Vo(2peak); from 13.9 +/- 3.6 to 18 +/- 2.7 ml/kg per min (A) and from 14.1 +/- 3.9 to 17.9 +/- 2.1 ml/kg per min (13), P< 0.001] and in HRR [from 17.1 +/- 1.8 to 23.4 +/- 1.4 beats/min (A), and from 18.8 +/- 2.1 to 24.3 +/- 1.9 beats/min (B), P< 0.001]. At 6 months' follow-up we observed a further improvement in VO2peak (from 18.0 +/- 2.7 to 20.3 +/- 2.7 ml/kg per min, P<0.001) and in HRR (from 23.4 +/- 1.4 to 27.8 +/- 2.1 beats/min,P<0.001) in group A, buta significant decrease in VO2peak and in HRR in group B (P<0.001). Conclusion Long-term exercise training is useful for maintaining or improving the beneficial results of the standard 3-month exercise training programme on cardiovascular capacity and HRR. This observation may bear beneficial prognostic effects on patients after AMI.