CAAN-AF: AV node ablation does not improve CRT outcomes

Design

International randomised controlled trial, stopped early for futility

Population

143 adults with HFrEF, permanent atrial fibrillation and a resynchronisation defibrillator

Primary outcome

Composite of all-cause mortality and non-fatal heart failure events

Effect

47 vs 46 events; incidence rate ratio 1.16 (95% CI 0.60-2.24)

Observational data had suggested that atrioventricular node ablation enhances cardiac resynchronisation therapy in patients with heart failure and atrial fibrillation. CAAN-AF tested it directly, randomising 143 patients with reduced ejection fraction, permanent atrial fibrillation and a resynchronisation defibrillator to ablation or medical rate control aimed at a resting heart rate below 90 beats per minute.

The trial was stopped early for futility. The primary composite of all-cause mortality and non-fatal heart failure events was essentially identical, 47 against 46 events, with an incidence rate ratio of 1.16 and a confidence interval that crossed 1.0. Cardiovascular mortality, unplanned hospitalisations, device-treated ventricular arrhythmias, six-minute walk distance and quality of life showed no significant differences either.

The practical message is to stop reaching for node ablation as a way to make resynchronisation work better. It remains a tool for rate control that medication cannot achieve, but not a routine step to improve outcomes.

• Randomised 143 patients with HFrEF, permanent atrial fibrillation and a resynchronisation defibrillator.
• Compared atrioventricular node ablation with medical rate control below 90 beats per minute.
• The trial was stopped early for futility.
• The death and heart failure composite was 47 versus 46 events (incidence rate ratio 1.16, 95% CI 0.60-2.24).
• No secondary outcome, including walk distance or quality of life, favoured ablation.

Why it matters

A randomised trial overturns the observational case for ablating to make CRT work better.

Don't overread it

The trial was small and stopped for futility, so it rules out a large benefit rather than a modest one, and does not mean ablation is never useful for symptomatic rate control.

The statistics, in plain English

An incidence rate ratio of 1.16 with a confidence interval from 0.60 to 2.24 straddles 1.0, meaning no benefit was detected and the data are compatible with a small effect either way. Stopping for futility means a prespecified analysis judged a positive result very unlikely if the trial continued.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.