Left bundle branch area pacing was non-inferior to biventricular pacing after AV node ablation

Design

Investigator-initiated, multicentre, randomised non-inferiority trial

Population

82 patients with refractory AF, LVEF below 50%, narrow QRS, undergoing AV node ablation

Primary outcome

Change in core-lab LVEF at 6 months

Effect

Difference 0.4 points (95% CI −3.1 to 3.8); non-inferiority P=0.002

CONDUCT-AF was an investigator-led trial across 10 European centres. It randomised 82 patients with refractory atrial fibrillation, ejection fraction below 50%, QRS of 120 ms or less and NT-proBNP above 600 ng/L to conduction system pacing with left bundle branch area pacing or to biventricular pacing, both after AV node ablation. Mean age was 72.

At six months, core-lab ejection fraction rose from 36% to 46% with conduction system pacing and from 34% to 46% with biventricular pacing. The between-group difference was 0.4 points (95% CI −3.1 to 3.8), meeting the non-inferiority margin. Ventricular volumes and the composite of worsening heart failure or cardiovascular death were similar. Paced QRS was 14 ms narrower, and procedure and fluoroscopy times were shorter, with conduction system pacing.

This supports conduction system pacing as a reasonable alternative to a biventricular device for the pace-and-ablate strategy, with one fewer lead in the coronary sinus. The trial was small and powered for a surrogate, so it cannot show equivalence for death or admissions.

Operator experience matters: success rates for left bundle branch area pacing vary by centre, and a biventricular system remains the standard where that expertise is not available.

• For pace-and-ablate in heart failure with AF, left bundle branch area pacing is a reasonable alternative to a biventricular device
• Expect similar ejection fraction recovery, about 10 points at six months, with either approach
• Factor in local operator experience with conduction system pacing before choosing it
• Recheck ejection fraction around six months after ablation and pacing to guide device and drug decisions
• Continue full guideline-directed heart failure therapy after the procedure

Why it matters

It removes much of the case for a coronary sinus lead in pace-and-ablate patients with narrow QRS.

Don't overread it

Ejection fraction is a surrogate; the trial was not powered for death or heart failure admission.

The statistics, in plain English

Non-inferiority means the worst plausible disadvantage for conduction system pacing (3.1 points of ejection fraction) was inside the margin the investigators set beforehand. With 82 patients, the trial cannot rule out small differences in hard outcomes such as death or admission.

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