EARLY AF

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Andrade J, et al. "Cryoablation or Drug Therapy for Initial Treatment of Atrial Fibrillation". The New England Journal of Medicine. 2021. 384:305-315.
PubMedFull textPDFClinicalTrials.gov

Clinical Question

In patients with atrial fibrillation, does catheter ablation reduce the recurrence of atrial arrhythmias compared to antiarrhythmics?

Bottom Line

Patients that underwent cryoablation were found to have a decreased rate of atrial fibrillation recurrence compared to those treated with antiarrhythmics.

Major Points

Trials have evaluated the safety and efficacy of catheter ablation for the treatment of atrial fibrillation after patients have already failed anti-arrhythmic therapy, but few have evaluated early catheter ablation.

The EARLY-AF trial showed that early ablation was safe and reduced the burden of atrial fibrillation at one year compared to drug therapy. The primary end point was recurrence of symptomatic or asymptomatic atrial tachyarrhythmia after a 90-day blanking period. There was no evidence of increase in serious averse events; in fact there was a trend towards decrease in adverse events comparing the ablation to anti arrhythmic groups.

The recent EAST-AFNET 4 trial found a decreased risk of the composite of CV mortality, stroke, HF or ACS hospitalization with a rhythm control strategy vs a rate control strategy in patients with recently diagnosed AF. Approximately 20% of patients in the rhythm-control group underwent ablation in that trial. Potentially the lower rate of atrial fibrillation lead to less negative remodeling. Therefore, the lower rate of atrial fibrillation burden found with catheter ablation compared to drug therapy in the EARLY-AF trial may lead to improvement in cardiovascular outcomes over the long-term, but notably this trial was not powered to answer this question. The study was published concurrently with the STOP AF First Trial, which was a similar trial performed in the US with similar findings.

Guidelines

As of May 2021, no guidelines have been published that reflect the results of this trial.

Design

  • Multicenter, open-label, end-point blinded, randomized, trial
  • N=303
    • Cryoablation (n=154)
    • Anti-arrhythmics (n=149)
  • Setting: 18 centers in Canada
  • Enrollment: January 17, 2017 to December 21, 2018
  • Mean follow-up: one year
  • Analysis: Intention-to-treat
  • Primary outcome: recurrence of any atrial tachyarrhythmia

Population

Inclusion Criteria

  • age >18 years
  • symptomatic atrial fibrillation and at least one episode of AF detected by rhythm monitoring within 24 months before randomization

Exclusion Criteria

  • daily use of class I or III anti-arrhythmic drug
  • previous left atrial ablation or surgery
  • atrial fibrillation due to reversible causes
  • active intracardiac thrombus
  • pre-existing pulmonary vein stenosis/stent
  • pre-existing heme-diaphragmatic paralysis
  • contraindication to anticoagulation or radiocontrast materials
  • moderately-severe or greater mitral valve disease
  • MI or coronary stent within three months of consent date
  • NYHA class III or IV CHF
  • EF < 35%
  • Hypertrophic cardiomyopathy
  • CKD stage IV or V
  • life expectancy less than one year

Baseline Characteristics

For Ablation group:

  • Mean age: 57.7 years
  • Sex: 72.7% male
  • Mean BMI: 30.9
  • Median year since diagnosis: 1
  • Symptomatic AF episodes/month: 3
  • CHA2DS2-VASc score: 1.9
  • Beta-blockers: 55.2%
  • non-DHP calcium channel blockers: 7.1%
  • previous use of class I or class III anti arrhythmic drug: 26.0%
  • oral anticoagulation:
    • warfarin: 3.2%
    • NOAC: 63.6%

Interventions

  • Randomized to catheter cryoablation with pulmonary-vein isolation vs anti-arrhythmic therapy.
    • all received implantable cardiac monitor
    • atrial tachyarrhythmia recurrence was not counted during first 90 days for either group

Outcomes

Comparisons are ablation vs anti-arrhythmic drug groups.

Primary Outcomes

Recurrence of symptomatic or asymptomatic atrial tachyarrhythmia after 90-day blanking period
42.9% vs 67.8% (HR 0.48; 95% CI 0.35-0.66)

Secondary Outcomes

Not adjusted for multiplicity

Recurrence of symptomatic atrial tachyarrhythmia
11.0% vs 26.2% (HR 0.39; 95% CI 0.22-0.68)
Median percent time in Atrial Fibrillation
0 (Interquartile range 0-0.08) vs 0.13 (IQR 0-1.60)
AFEQT symptom survey change in baseline at 12 months
26.9 +/- 1.9 vs 22.9 +/- 2.0 (Treatment effect 8.0+/-2.2)


Subgroup Analysis

Treatment effect did not vary significantly when comparing predefined subgroups by ablation experience, left atrial enlargement presence, or duration of AF.

Adverse Events

Selected adverse event rates are shown below; see the article for a full listing

Any adverse serious adverse event related to the trial regimen
3.2% vs. 4.0%

Criticisms

  • The use of a single ablation technology in the trial reduces the generalizability toward other ablation energy sources.
  • Long-term effect of early ablation on atrial fibrillation progression, healthcare utilization, and cost-effectiveness could not be evaluated due to the limited follow-up length of 1 year.
  • The change in atrial fibrillation burden from baseline was not evaluated in the trial.

Funding

  • The study was funded by the Cardiac Arrhythmia Network of Cannada, Medtronic, Baylis Medical, and the University of British Columbia.

Further Reading