Heart rate increase during exercise was strongly associated with peak oxygen consumption (β: 0.572, P<0.0001) and NYHA class (β: -0.499, P<0.0001) regardless of beta-blocker therapy or dose.
Observational (n=639)
Does beta-blocker therapy or dose affect the relationship between chronotropic incompetence and functional capacity in patients with chronic heart failure?
Heart rate increase during exercise is a powerful predictor of heart failure severity and functional capacity, independent of beta-blocker use or dose.
AIM: To assess the effect of chronotropic incompetence on functional capacity in chronic heart failure (CHF) patients, as evaluated as NYHA and peak oxygen consumption (pVO(2) ), focusing on the presence and dose of β-blocker treatment. METHODS: Nine hundred and sixty-seven consecutive CHF patients were evaluated, 328 of whom were discarded because they failed to meet the study criteria. Of the 639 analyzed, 90 were not treated with β-blockers whereas the other 549 were. The latter were further subdivided in high (n = 184) and low (n = 365) β-blockers daily dose group in accordance with an arbitrary cut-off of 25 mg for carvedilol and of 5 mg for bisoprolol. Failure to achieve 80% of the percentage of maximum age predicted peak heart rate (%Max PHR) or of HR reserve (%HRR) constituted chronotropic incompetence. RESULTS: No differences were found in NYHA or pVO2 between patients with and without β-blockers and, similarly, between high and low β-blocker dose groups. Twenty and sixty-nine percent of not β-blocked patients showed chronotropic incompetence according to %Max PHR and %HRR, respectively, whereas this prevalence rose to 61% and 84% in those on β-blocker therapy. Patients taking β-blockers without chronotropic incompetence, as inferable from both %Max PHR and %HRR, showed higher NYHA and pVO2 regardless of drug dose, whereas, in not β-blocked patients, only %HRR revealed a difference in functional capacity. At multivariable analysis, HR increase during exercise (ΔHR) was the variable most strongly associated to pVO2 (β: 0.572; SE: 0.008; P < 0.0001) and NYHA class (β: -0.499; SE: 0.001; P < 0.0001). CONCLUSIONS: ΔHR is a powerful predictor of CHF severity regardless of the presence of β-blocker therapy and of β-blocker daily dose.
Magrì et al. (Fri,) conducted a observational in Chronic heart failure (CHF) (n=639). Beta-blocker therapy vs. No beta-blocker therapy was evaluated on Functional capacity evaluated as NYHA class and peak oxygen consumption (pVO2). Heart rate increase during exercise was strongly associated with peak oxygen consumption (β: 0.572, P<0.0001) and NYHA class (β: -0.499, P<0.0001) regardless of beta-blocker therapy or dose.