Heart rate determines the beneficial effects of beta-blockers on cardiovascular outcomes in patients with heart failure and atrial fibrillation.

Beta-blockers are recommended as a standard therapy for patients with heart failure (HF). However, beta-blockers are reportedly less effective in HF patients with atrial fibrillation (Af) compared with those with sinus rhythm (SR). Here, we investigated whether HR at discharge determined the cardiovascular outcomes in HF patients with Af treated with beta-blockers. In this analysis, we enrolled 97 HF patients with concomitant Af. These patients were divided into 6 groups according to beta-blocker use and tertiles of discharge HR: lowest <60 beats per minute (bpm), middle 61-70 bpm and highest >71 bpm. The primary endpoint was defined as a composite of rehospitalization due to worsening of HF and all-cause mortality. During a median follow-up of 772 days after discharge, the composite cardiovascular outcome occurred in 37 (61%) and 25 (69%) patients with or without beta-blockers, respectively. In the Cox proportional hazard analysis, the lowest HR tertile in patients with beta-blockers was associated with an increased risk of the composite outcome compared with the middle and highest tertiles in both the unadjusted model (hazard ratio: 2.568, 95% confidence interval (CI): 1.089-6.057, p = 0.031; hazard ratio: 2.024, 95% CI: 0.921-4.447, p = 0.079, respectively) and the model adjusted for potential confounders (hazard ratio: 2.631, 95% CI: 1.078-6.421, p = 0.034; hazard ratio: 2.876, 95% CI: 1.147-7.207, p = 0.024, respectively). In patients with HF and Af receiving beta-blockers, low HR adversely increased the risk of cardiovascular events. This fact may blunt the beneficial effects of beta-blockers in patients with HF and Af.