Dose Limiting, Adverse Event Associated Bradycardia with β-blocker Treatment of Atrial Fibrillation in the GENETIC-AF Trial

ABSTRACT Background Heart failure (HF) patients with atrial fibrillation (AF) often have conduction system disorders, which may be worsened by β-blocker therapy. Objective In a post-hoc analysis we examined the prevalence of bradycardia and its association with adverse events (AEs) and failure to achieve target dose in the GENETIC-AF trial. Methods Patients randomized to metoprolol (N=125) or bucindolol (N=131) entering 24-week efficacy follow-up and receiving study medication were evaluated. Bradycardia was defined as an ECG heart rate (HR) Results Mean HR in sinus rhythm (SR) was 62.6±12.5 bpm for metoprolol and 68.3±11.1 bpm for bucindolol (P Conclusion In AF-prone HF patients bradycardia may limit the effectiveness of β-blockers, and this property is agent-dependent.