THE EFFECT OF BETA-BLOCKADE THERAPY ON THE RESPONSE TO EXERCISE TRAINING IN POSTMYOCARDIAL INFARCTION PATIENTS

Cardiac rehabilitation after a myocardial infarction has been shown to improve exercise capacity Beta blockade has been shown to be effectiv e in treating angina and reducing mortality, but studies are controver sial as to whether beta-blockade therapy attenuates the effects of tra ining. We attempted to study the effects of beta blockade (metoprolol) on the response to training in patients enrolled in a cardiac rehabil itation program after an uncomplicated myocardial infarction. We studi ed 27 patients with a recent uncomplicated myocardial infarction who w ere subdivided in two,groups: Group 1 (13 patients) not taking a beta blocker, and Group 2 (14 patients) taking metoprolol (mean 142 +/- 57 mg daily). All patients underwent a maximal cardiopulmonary exercise t est before and after a 3-month training program. The training intensit y was designed to approximate the ventilatory threshold. Results showe d an increase in peak VO2 in both Group 1 (27%, p < 0.01) and Group 2 (33%, p < 0.001), and an increase in VO2 at the ventilatory threshold (39% in Group 1 and 28% in Group 2, p < 0.01). The mean changes in exe rcise capacity were not different between groups. It was concluded tha t metoprolol did not influence the beneficial effects of a cardiac reh abilitation program in postmyocardial infarction patients.