Cardiac resynchronization therapy and AV node ablation in heart failure with reduced ejection fraction and atrial fibrillation: rationale and design of the CAAN-AF trial

Background: Cardiac resynchronization therapy (CRT) is an important treatment modality for patients with symptomatic heart failure (HF) with reduced ejection fraction (HFrEF) and QRS prolongation on electrocardiogram. However, patients with atrial fibrillation (AF) appear to benefit less from CRT compared to patients in sinus rhythm. Atrioventricular (AV) node ablation has been shown in observational studies to improve the efficacy of CRT in patients with AF. Objective: We aimed to evaluate the effect of AV node ablation on CRT efficacy in patients with permanent AF. Methods: Participants with permanent AF and a reduced left ventricular ejection fraction (≤35%) who receive a CRT-defibrillator are randomized in a 1:1 fashion to AV node ablation or medical rate control for treatment of AF. A sample size of 590 participants allows a detection of a 25% reduction in the primary end point at 80% power. Results: The primary end point is a composite of all-cause mortality and non-fatal HF events after 2 years of follow-up. The secondary end points include all-cause mortality, cardiovascular mortality, non-fatal HF events, 6-minute walking distance, quality-of-life, unscheduled hospitalizations, ventricular arrhythmias requiring device therapies, and biventricular pacing percentage. Conclusion: The CRT And AV Node ablation trial in AF (CAAN-AF) will be the first randomized controlled trial to investigate the effect of AV node ablation on CRT efficacy in patients with AF and HFrEF. The results will guide physicians regarding the use of AV node ablation for patients with CRT and AF.