Conduction system 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 <50%, QRS ≤120 ms, undergoing AV node ablation

Primary outcome

Change in LVEF at 6 months (core laboratory)

Effect

36%→46% vs 34%→46%; difference 0.4% (95% CI −3.1 to 3.8), non-inferior

CONDUCT-AF was an investigator-initiated randomised trial at 10 European centres. It enrolled 82 patients, mean age 72, with refractory atrial fibrillation, heart failure with LVEF below 50%, QRS of 120 ms or less and NT-proBNP above 600 ng/L, all undergoing atrioventricular node ablation. They were randomised to left bundle branch area pacing or biventricular pacing, with LVEF change at six months read in a core laboratory as the primary endpoint.

LVEF rose from 36% to 46% with conduction system pacing and from 34% to 46% with biventricular pacing. The difference of 0.4 percentage points (95% CI −3.1 to 3.8) met the non-inferiority margin. Ventricular volumes, clinical measures and the composite of worsening heart failure or cardiovascular death were similar. Paced QRS was 14 ms narrower with left bundle pacing, and procedure and fluoroscopy times were shorter.

The trial is small and powered on an echo endpoint, not on clinical events, so it cannot show the two strategies are equal for hospitalisation or survival. What it does show is that the simpler, single-lead physiological approach restores ventricular function as well as a biventricular system in this setting. Where an operator is experienced in left bundle branch area pacing, it is a reasonable first choice for 'ablate and pace'.

• For 'ablate and pace' with reduced ejection fraction, consider left bundle branch area pacing where the operator is experienced.
• Expect a similar LVEF improvement, about 10 points at six months, with either approach.
• Conduction system pacing shortened procedure and fluoroscopy time, which matters in frail older patients.
• Keep biventricular pacing available as a fallback when left bundle capture cannot be achieved.
• Clinical-event equivalence is not established; follow these patients as closely as any device recipient with heart failure.

Why it matters

A single-lead physiological system may now be enough where a three-lead device was the default.

Don't overread it

The primary endpoint was LVEF at six months, not hospital admission or death.

The statistics, in plain English

Non-inferiority means the trial showed conduction system pacing is not worse than biventricular pacing by more than a prespecified margin; it does not mean it is better. With 82 patients, the comparison of clinical events is too small to be informative.

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