Intensive home-based exercise training in cardiac rehabilitation increasesexercise capacity and heart rate variability

Background: Reduced heart rate variability (HRV) is a risk factor for cardi ac death. Animal studies have shown increased HRV and reduced mortality aft er physical training. We evaluated the change in exercise capacity and HRV in cardiac rehabilitation patients, randomised to routine or home-based int ensive training. The design was prospective, stratified randomisation with pre-specified subgroup analysis. Methods: Maximal bicycle exercise test and 24-h Holter were performed 1 (baseline). 4 and 12 months after myocardial infarction (MI) or coronary artery by-pass surgery (CABG). Patients were ra ndomised to physical training either two (N) or six (I) times per week for 3 months Sixty-two patients (43 MI and 19 CABG patients) were evaluated. Re sults: Exercise capacity increased significantly more after 3 months of tra ining in group I (mean ((S.E.); 29.0 (3.4) vs. 7.2 (2.6) watts, P < 0.001). One year later the difference in exercise capacity remained (26.5 (3.3) vs . 11.8 (3.8) watts, P < 0.001). Global HRV measurements SDNN and SDANN incr eased significantly more in group I after training (17.1 (5.6) vs. 1.7 (3.7 ) and 16.2 (4.9) vs. 2.8 (3.1) ms, P < 0.05) and 1 year later the differenc es were still significant. Subgroup analysis showed more pronounced HRV res ponse in CABG than MI patients. Conclusion: Intensive exercise training in cardiac rehabilitation increases exercise capacity and global HRV, which co uld be of prognostic significance. (C) 2001 Elsevier Science Ireland Ltd. A ll rights reserved.