BERN, SWITZERLAND. It is generally assumed that candidates for catheter ablation of atrial fibrillation (AF) have failed therapy with at least one antiarrhythmic drug (AAD). However, recently published guidelines allow for AF ablation as an initial therapy prior to AAD in symptomatic paroxysmal AF patients with no significant underlying heart disease, who remain highly symptomatic, despite rate control, and reject AAD therapy.

Now a group of electrophysiologists at the University Hospital in Bern reports that ablation success rates are higher in patients who go directly to an ablation than in those who try one or more antiarrhythmic drugs before going the ablation route. Their study involved 434 AF patients with an average age of 58 years. The majority (68%) had paroxysmal AF, 56% had lone AF, 53% had hypertension, and 78% were male. The majority (362 patients – 83%) had tried at least one antiarrhythmic drug without success prior to being scheduled for ablation, while the remaining 72 patients (17%) went straight for the ablation. The members of the drug group (AAD group) had suffered from AF for a considerably longer period (78 months vs. 52 months) prior to ablation than had the ablation first group (ablation group). They were also more likely to have had cardioversions and hospitalizations than were members of the ablation group.

All study participants underwent a circumferential pulmonary vein isolation (CPVI) procedure with additional lesions as required and were then followed for an average of 16 months (from last procedure) during which time ECGs, event recording, or Holter monitoring was used to determine success or failure of the procedure. ECGs were also done to confirm symptomatic episodes reported by patients. After excluding atrial tachyarrhythmias (AF, atrial flutter, and atrial tachycardia) during a 3-month blanking period, 59% of the ablation group was in normal sinus rhythm vs. 39% in the AAD group (with or without antiarrhythmic therapy). An enlarged left atrium (parasternal diameter) and female gender were associated with a poorer success rate.

A second CPVI was performed in 38% of the AAD group vs 21% of the ablation group. An average of 16 months following the last procedure, the final complete success rates (no AF, no antiarrhythmics) in the AAD group and ablation group were 41% and 63% respectively. The partial success rate (no AF, but still on antiarrhythmics after 3-month blanking period) was 23% for the AAD group and 15% for the ablation group.

The Swiss researchers conclude that performing catheter ablation at an earlier stage of AF progression results in a significantly higher success rate and a reduced need for repeat procedures.

Tanner, H, Delacretaz, E, et al. Catheter ablation of atrial fibrillation as first-line therapy – a single-centre experience. Europace, Vol. 13, 2011, pp. 646-53

Editor's comment: The findings of this study make imminent sense in that, the longer AF is allowed to continue, the more extensive electrical and structural remodeling there is likely to be, resulting in a poorer outcome of catheter ablation.