Beta-blocker therapy and physical activity after myocardial infarction: a preplanned sub-study of the BETAMI trial

AIMS: To investigate the effect of long-term beta-blocker therapy on physical activity (PA) level after myocardial infarction (MI) in patients without heart failure. METHOD: The BETAMI trial, randomised patients hospitalised with a MI without heart failure (LVEF ≥40%) to beta-blocker or no beta-blocker. In this pre-planned sub-study PA level was assessed by guideline-recommended PA level (≥30 minutes moderate activity ≥5 days/week) or not and self-reported hours/week with light to moderate and vigorous PA. Between-group differences in PA from baseline before randomisation to 18-months were estimated by linear mixed models. Exploratory analysis assessed treatment effects on a composite of all-cause mortality and major adverse cardiovascular events using Cox proportional hazards model. RESULTS: Of the 2867 randomised patients, 2185 (76%) responded to the PA questions and were included in this analysis. Mean age was 62.5 (SD 10.1) years, 20.6% were women. No differences in guideline-recommended PA level or mean hours of light to moderate and vigorous PA were reported between the beta-blocker and non-beta-blocker group at baseline or during 18-months follow-up. At 12-month follow-up, 37.0% in the beta-blocker group and 36.7% in the no beta-blocker group reported guideline-recommended PA level (OR 0.97, 95% CI 0.69-1.37). Exploratory, hypothesis-generating analyses did not demonstrate a statistically significant interaction (p for interaction = 0.06) between treatment assignment and baseline PA level for recurrent clinical events. CONCLUSIONS: Beta-blocker therapy did not result in a change in PA level in post-MI patients without heart failure during the 18 months follow-up.