Catheter ablation reduces AF recurrence and AF burden
Recurrence of Atrial Fibrillation After Catheter Ablation or Antiarrhythmic Drug Therapy in the CABANA Trial
Introduction and methods
Over the years, catheter ablation for AF has become increasingly accepted as a first-line treatment strategy for a broad group of AF patients [1-3]. Reasons thereof are progress in reducing serious procedural risks of catheter ablation and recognition of pulmonary vein isolation as an important procedure for successful AF ablation. However, difficulties in detecting recurrence of AF has caused controversy regarding the durability of AF suppression after catheter ablation [4-12].
The Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation (CABANA) trial evaluated efficacy of catheter ablation compared to drug therapy in reducing primary outcome of a composite of death, disabling stroke, serious bleeding or cardiac arrest in 2204 patients with symptomatic AF . Analysis by intention-to-treat showed a nonsignificant 14% relative reduction in the primary endpoint (HR 0.86, 95%CI 0.65-1.15; P=0.303). A secondary objective of the CABANA trial was to evaluate the long-term risk of AF recurrence and overall AF burden in patients treated with catheter ablation compared with drug therapy. Initial results of the CABANA trial demonstrated a significant 48% reduction in AF recurrence with follow-up to 48 months.
This study reported an expanded analysis, with follow-up to 5 years, of patients (n=1240) in the CABANA trial regarding compared effects of catheter ablation (n=611) and drug therapy (n=629) on AF recurrence and AF burden gathered with 24-h transtelephonic monitor (TTM) and biannual 96-h Holter recordings. Atrial tachyarrhythmias (symptomatic AF, any AF [symptomatic or asymptomatic] and the composite of AF, atrial flutter [AFL] or atrial tachycardia [AT]) lasting ≥30 seconds were analyzed in data collected >90 days after receiving the randomized treatment. Holter monitoring was used to assess AF burden, defined as average percentage of time in AF relative to total analyzable patient Holter recording time. Time-to-event comparisons between treatment groups were performed using a modified intention-to-treat (mITT) approach.
- By 12 months, recurrence of symptomatic AF occurred in 12.6% of ablation patients and 27.5% of drug therapy patients, and a first recurrence of any AF occurred in 36.4% of ablation patients and 59.2% of drug therapy patients. Over 5 years of follow-up, 18.4% of ablation patients and 23.1% of drug therapy patients who had a recurrence experienced a first recurrence that was symptomatic.
- Over 5 years of follow-up, catheter ablation was associated with a significant reduction in recurrence of symptomatic AF (HR 0.49, 95%CI 0.39-0.61; P <0.001) and recurrence of any AF (HR 0.52, 95%CI 0.45-0.60; P <0.001).
- Catheter ablation was associated with 47% reduction in time to first recurrence of composite AF, AFL, or AT (HR 0.53, 95%CI 0.46-0.62; P <0.001) as compared to drug therapy. There was no substantial contribution of AFL and AT to the first recurrent atrial arrhythmia.
- Baseline AF burden in both treatment groups was 48%. At 12 months, average AF burden was 6.3% in ablation patients and 14.4% in drug therapy patients. At 5 years, average AF burden was 14.7% in ablation patients and 20.8% in drug therapy patients. Across the 5 years follow-up, AF burden was significantly less in ablation patients as compared to drug therapy patients (P <0.01). These findings were not sensitive to baseline AF pattern (paroxysmal or persistent/long-standing persistent).
This expanded analysis of the CABANA trial reported, across a 5 year follow-up period, a significant reduction of recurrent symptomatic and asymptomatic AF after catheter ablation as compared to drug therapy. In addition, average AF burden was significantly reduced in catheter ablation patients as compared to drug therapy patients, regardless of baseline AF type.