REDWOOD CITY, CALIFORNIA. Most guidelines for the management of atrial fibrillation (AF) specify that patients should not be considered for a catheter ablation unless treatment with at least one antiarrhythmic drug (AAD) has proven ineffective in controlling their condition. The 2010 European guidelines suggested that paroxysmal afibbers could proceed directly to ablation without having tried AADs, if they are symptomatic even with rate control and have no underlying heart disease. Similarly, the 2011 Canadian guidelines allow for first-line ablation for symptom relief in highly selected patients with paroxysmal AF. Now a group of electrophysiologists (EPs) from Sequoia Hospital and Silicon Valley Cardiology suggests that the outcome of an ablation becomes less favourable the more antiarrhythmics the patient tries prior to having the ablation.

Their study involved 1125 AF patients who had undergone a total of 1504 catheter ablation (average of 1.3 procedures per patient) during the period 2003 to 2010. Most patients (53%) in this particular group had persistent AF, 31% had the paroxysmal variety, and the remaining 16% had permanent AF. The average age of the patients was 62 years and 29% were female. Four hundred patients had tried one AAD, 231 had tried two, 115 had tried 3 or more, and the remaining 195 had never been on any AAD prior to their initial ablation. A significant proportion of the group had coronary artery disease (14%), hypertension (47%), dilated cardiomyopathy (8%), or had suffered a stroke or TIA (7%). So, it was not a terribly healthy group of patients and certainly not comparable in characteristics to a group of otherwise healthy afibbers.

The researchers observed that patients who failed several AADs were older, had been suffering from AF longer, were more likely to be female, and were more likely to have persistent rather than paroxysmal AF. They also noted that the extent of drug failure was directly related to an increase in the need for repeat ablations. The overall complete success rate (no AF, no ADDs after a 3-month blanking period) at one year from the initial ablation was 68.9% for patients who had never been on AADs vs. 42.8% for those who had failed 3 or more AADs (paroxysmal and persistent afibbers combined). Corresponding numbers at the 4-year mark (from Kaplan-Meier curves) was 61.3% and 29.4%. Other statistically significant predictors of initial ablation failure were an enlarged left atrium, female gender, and persistent AF. The number of pre-ablation failed AADs did not affect the outcome of ablations in permanent afibbers.

Major procedure-related complications occurred in 1.6% of procedures with pericardial tamponade being the most common. There were no procedure-related deaths, PV stenosis requiring intervention, or atrial-esophageal fistulae. The researchers speculate that the additional time elapsed during the trial of one or more AADs allows for disease progression from paroxysmal to more persistent AF and thus reduces the chance of a successful ablation outcome. They suggest that EPs should not actively discourage patients from having an ablation if they do not wish to try AADs first.
Winkle, RA, et al. Prior antiarrhythmic drug use and the outcome of atrial fibrillation ablation. Europace, Vol. 14, 2012, pp. 646-52

Editor's comment: I believe this report carries two important messages:

• Don't wait for your left atrium to enlarge beyond about 4 cm (40 mm) in diameter before undergoing an ablation.
• Go for an ablation as first-line treatment, or if you have failed one antiarrhythmic. Chances are that a different AAD won't work either, and that postponing an ablation will result in a poorer outcome.