Heart rate reduction and exercise performance in recent onset heart failure with reduced ejection fraction: arguments for beta-blocker hypo-response

Abstract

Objective Beta blockers reduce all-cause mortality and readmissions in heart failure with reduced ejection fraction (HFrEF), which may be explained by their eff ect on heart rate (HR). This study assessed the impact of HR reduction with beta blockers on exercise capacity in recent onset HFrEF.

Methods and results Fifty consecutive patients with recent onset HFrEF (< 30 days) performed a standardized exercise protocol with respiratory gas analysis at baseline as well as after 6 and 12 months. Patients participated in a quality of care programme aiming to achieve guidelinerecommended target doses for beta-blocker therapy. At baseline, 6 and 12 months, 36%, 70% and 62% of patients, respectively, had a resting HR < 70 bpm. Beta-blocker dose after 12 months was comparable in patients with resting HR < 70 versus ≥ 70 bpm (P value = 0.631). However, with similar dose uptitration, the former versus the latter had a signifi cantly larger HR reduction (17 ± 22 versus 4 ± 15 bpm; P value = 0.027). Peak oxygen consumption (VO_2max) was signifi cantly higher when resting HR was < 70 versus ≥ 70 bpm (17.5 ± 5.5 versus 14.4 ± 3.3 mL/min/kg, respectively; P value = 0.038). Similar results were observed after 6 months. Patients in whom resting HR decreased at follow-up compared to baseline had a 2.0 ± 3.2 mL/min/kg increase in VO_2max compared to a 1.2 ± 7.7 mL/min/kg increase in patients who did not demonstrate a lower resting HR (P value = 0.033).

Conclusions In recent onset HFrEF, exercise performance was better when resting HR was controlled < 70 bpm with beta-blocker therapy. However, despite aggressive dose uptitration, many patients did not achieve this target as they had little HR reduction with beta-blocker therapy.

Key Words:

• Adrenergic beta antagonists
• exercise tolerance
• heart rate
• systolic heart failure