Catheter Ablation of atrial fibrillation vs. atrioventricular nodal ablation with Conduction system pacing in persistent atrial fibrillation and heart failure (ABACUS): rationale and design.

Aims: Patients with persistent atrial fibrillation (AF) and heart failure (HF) have compromised clinical outcomes. Contemporary management includes rhythm control with AF ablation, or rate control and regularization with conduction system pacing and atrioventricular nodal ablation (CSP + AVNA). These strategies have never been compared in a randomized clinical trial. The study aims to determine whether CSP + AVNA is superior to AF ablation for reducing all-cause mortality and cardiovascular hospitalization, and noninferior with respect to all-cause mortality and heart failure hospitalization. Methods and results: ABACUS is a multicentre, investigator-initiated, randomized controlled trial enrolling 220 patients with persistent AF and HF, aged >60 years, who are eligible for both treatment modalities, with at most one previous AF ablation procedure. Participants will be randomized 1:1 to either catheter ablation of AF (with pulmonary vein isolation using any routine technique) or to CSP + AVNA. All patients will undergo at least one year of follow-up. The co-primary endpoints will be tested sequentially. A number of predefined secondary endpoints, including costs, will also be evaluated. Discussion: ABACUS compares CSP + AVNA with AF ablation in patients with persistent AF and HF. The results will provide evidence to improve care in this vulnerable patient population.