Higher beta-blocker dose was positively associated with 6-minute walk test distance in post-MI patients with atrial fibrillation (B = 7.55, p = 0.04), but not in those without AF.
Cohort (n=117)
Does atrial fibrillation modify the relationship between beta-blocker dose and physical capacity in post-myocardial infarction patients?
Higher beta-blocker doses are associated with improved functional capacity in post-MI patients with atrial fibrillation, but not in those with normal sinus rhythm.
Effect estimate: B = 7.55
p-value: p=0.04
Background: Atrial fibrillation (AF) is a common arrythmia in post-myocardial infarction (MI) cardiac rehabilitation (CR) cohorts, and beta-adrenergic signaling remodeling and rate-control pharmacotherapy may influence functional capacity. Methods: We retrospectively studied 117 consecutive male post-MI patients referred to outpatient CR. Functional capacity was assessed with a 6 min walk test (6MWT). AF was identified from clinical records, and beta-blocker exposure was unified as carvedilol-equivalent daily dose. Results: Beta-blockers were used in 94.1% of patients and AF was present in 10.3%. Patients with AF were older (72.7 ± 6.6 vs 58.1 ± 9.3 years) and walked shorter distances (430.0 375.0–497.5 vs. 540.0 480.0–570.0 m). In the prespecified interaction model, age remained independently associated with lower 6MWT (−4.29 m/year; p < 0.001), AF was associated with lower 6MWT (−137.21 m; p = 0.01), and the beta-blocker dose × AF interaction was positive (+6.78; p = 0.02; R2 = 0.44). Importantly, the beta-blocker dose was not associated with 6MWT in patients without AF, whereas a positive association was observed in AF (B = 7.55, p = 0.04). Conclusions: In this exploratory analysis, AF identified a subgroup with markedly reduced functional capacity in early post-MI CR, supporting the potential of phenotype-informed assessment. Additionally, the association between beta-blocker dose and 6MWT distance differed by rhythm status. These preliminary findings require confirmation in larger prospective cohorts.
Rabiej-Krzyś et al. (Sat,) conducted a cohort in Post-myocardial infarction (n=117). Beta-blocker dose vs. Patients without atrial fibrillation was evaluated on Functional capacity assessed with a 6-minute walk test (6MWT) (B = 7.55, p=0.04). Higher beta-blocker dose was positively associated with 6-minute walk test distance in post-MI patients with atrial fibrillation (B = 7.55, p = 0.04), but not in those without AF.