Background: Myocardial ischemia and infarction impair baroreflex sensitivity (BRS), which when depressed is predictive of future cardiac events after myocardial infarction (MI). The main objective of this study was to determine whether exercise training improves BRS in patients with coronary artery disease.
Methods and results: Ninety-seven male patients with and without a previous MI were recruited after myocardial revascularization surgery and randomized into trained (TR) or untrained (UTR) groups. TR patients underwent a residential exercise program at 85% of maximum heart rate (HRmax) consisting of 2 daily sessions 6 times a week for 2 weeks. Eighty-six patients (45 TR and 41 UTR) completed the study. BRS was assessed at baseline and at the end of the protocol by the spontaneous baroreflex method. The standard deviation of mean R-R interval (RRSD) was also assessed as a measure of heart rate variability. At baseline, there were no significant differences between TR and UTR patients in any variable. In TR patients, BRS increased from 3.0+/-0.3 to 5.3+/-0.7 ms/mm Hg (P:<0.001), RRSD from 18.7+/-1.4 to 23.6+/-1.6 ms (P:<0.01), and R-R interval from 792. 0+/-15.5 to 851.3+/-20.5 ms (P:<0.001). No significant changes occurred in UTR patients. Increases in BRS and RRSD were significant in patients either with or without a previous MI.
Conclusions: Exercise training increases BRS and heart rate variability in patients with coronary artery disease. Improved cardiac autonomic function might add to the other benefits of exercise training in secondary prevention of ischemic heart disease.