What question did this study set out to answer?

The study aims to assess the effectiveness of conduction system pacing with atrioventricular nodal ablation versus catheter ablation in patients with persistent atrial fibrillation and heart failure.

January 22, 2026Open Access

Catheter ABlation of Atrial fibrillation versus atrioventricular nodal ablation with CondUction System pacing in persistent atrial fibrillation and heart failure (ABACUS): rationale and design

Key Result

The trial aims to determine whether CSP+AVNA is superior to AF ablation in reducing all-cause mortality and cardiovascular hospitalization in patients with persistent AF and heart failure.

Key Points

The study aims to assess the effectiveness of conduction system pacing with atrioventricular nodal ablation versus catheter ablation in patients with persistent atrial fibrillation and heart failure.
Multicentre, randomised controlled trial design
Enrolling 220 patients aged over 60 years with persistent AF and HF
Participants randomised 1:1 to receive either catheter ablation or CSP+AVNA
Follow-up duration of at least one year
Evaluation of predefined co-primary and secondary endpoints, including costs.
CSP+AVNA aims to reduce all-cause mortality and hospitalisation due to cardiovascular events compared to AF ablation.
Non-inferiority for all-cause mortality and heart failure hospitalisation is planned to be assessed.
Results will inform better care approaches for patients with persistent AF and HF.

Structured PICO

Does conduction system pacing and atrioventricular nodal ablation improve outcomes compared to catheter ablation of AF in patients over 60 with persistent AF and heart failure?

Population

220 patients with persistent atrial fibrillation (AF) and heart failure (HF), aged >60 years, who are eligible for both treatment modalities, with at most one previous AF ablation procedure.

Intervention

Conduction system pacing and atrioventricular nodal ablation (CSP+AVNA)

Comparator

Catheter ablation of AF (with pulmonary vein isolation using any routine technique)

Outcome

Co-primary endpoints: all-cause mortality and cardiovascular hospitalisation (superiority testing), and all-cause mortality and heart failure hospitalisation (non-inferiority testing)composite

The ABACUS trial will provide randomized evidence comparing conduction system pacing with AV node ablation versus AF ablation in older patients with persistent AF and heart failure.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

Abstract Background 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 regularisation with conduction system pacing and atrioventricular nodal ablation (CSP+AVNA). These strategies have never been compared in a randomised clinical trial. Aims The study aims to determine whether CSP+AVNA is superior to AF ablation for reducing all-cause mortality and cardiovascular hospitalisation, and non-inferior with respect to all-cause mortality and heart failure hospitalisation. Methods ABACUS is a multicentre, investigator-initiated, randomised 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 randomised 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.