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Demonstration of training effect during chronic beta-adrenergic blockade in patients with coronary artery disease
Insights
Patients with coronary artery disease (CAD) can achieve significant exercise training benefits even when taking beta-blockers. This study shows that cardiac rehabilitation is effective despite reduced heart rates during exercise.
Area of Science:
- Cardiology
- Exercise Physiology
- Pharmacology
Background:
- Beta-adrenergic blockade in patients with coronary artery disease (CAD) may potentially limit exercise training benefits by attenuating exercise-induced heart rate and cardiac output.
- Understanding the impact of beta-blockers on exercise capacity and training adaptations is crucial for optimizing cardiac rehabilitation programs.
Purpose of the Study:
- To assess the efficacy of a 3-month exercise training program in CAD patients receiving varying doses of beta-blockers.
- To determine if beta-blocker therapy compromises the benefits of exercise training in this population.
Main Methods:
- A 3-month walk-jog-cycle training program was implemented in 35 CAD patients divided into three groups: no beta-blocker, low-dose propranolol, and high-dose propranolol.
- Maximal exercise heart rate and oxygen consumption (VO2 max) were measured before and after the training intervention.
- Training intensity was maintained at 70-85% of the maximal pretraining heart rate.
Main Results:
- All groups showed significant increases in VO2 max after training (27% in no beta-blocker, 30% in low-dose, 46% in high-dose).
- Maximal exercise heart rate was significantly lower in both propranolol groups compared to the no beta-blocker group.
- Despite reduced training heart rates in beta-blocker groups, substantial training effects were observed.
Conclusions:
- Substantial exercise training benefits can be achieved in CAD patients even with therapeutic doses of beta-blockers and reduced training heart rates.
- There is no apparent need to reduce beta-blocker dosages in CAD patients undergoing cardiac rehabilitation.
- Beta-blocker therapy does not appear to compromise the positive adaptations from exercise training in coronary artery disease patients.
Abstract:
Attenuation of exercise-induced increases in heart rate and cardiac output by chronic beta-adrenergic blockade has been thought to compromise benefit of exercise training in patients with coronary artery disease (CAD). To assess this important issue, 35 CAD patients were evaluated by a 3-month walk-jog-cycle training program: 14 patients received no beta blocker (group 1), 14 received propranolol, 30-80 mg/day (group 2), and seven patients received propranolol, 120-240 mg/day (group 3). The extent of CAD, resting heart rate before training blood pressure and VO2 max were similar (p = NS) in each group. The maximal exercise heart rate (mean +/- SD, 147 +/- 21 beats/min in group 1 vs 120 +/- 10 beats/min in group 2 and 115 +/- 12 beats/min in group 3 (both p less than 0.05 vs group 1). The VO2 max before training was 25 +/- 5.0 ml/kg/min in group 1 vs 23 +/- 3.2 ml/kg/min in group 2 and 26 +/- 2.8 ml/Kg/min in group 3 (all p = NS). Training consisted of three 1-hour periods per week at a heart rate of 70-85% of the maximal pretraining heart rate. In each group, VO2 increased (p less than 0.05) after training: group 1, 27%; group 2, 30%; group 3, 46%. The double product was unchanged after training (p = NS) in each group. These data indicate that substantial training effects may be achieved in CAD patients despite therapeutic doses of beta blockers and a reduced training HR. Thus, there appears to be no indication to reduce beta blockers in CAD patients engaged in cardiac rehabilitation.