Definition of ablation failure

EAST PALO ALTO. CALIFORNIA. The “official” (Heart Rhythm Society) definition of ablation failure is the occurrence of a single arrhythmia (atrial fibrillation, atrial flutter, atrial tachycardia) episode lasting longer than 30 seconds, usually following a post-ablation blanking period of 3 months. This definition is quite arbitrary, and far stricter than the criterion used to define failure of treatment with antiarrhythmic drugs. It is also totally unrealistic from the patient’s point of view.

A group of electrophysiologists at Silicon Valley Cardiology now suggests that a better definition of ablation failure would be an AF burden (episode frequency multiplied by duration) of more than 0.5% when measured over a longer term (7 days of event monitoring, or 1 year of pacemaker interrogation). Their recommendation for the change in ablation failure definition is based on a study carried out to determine the actual incidence of AF in a group of 203 patients who had undergone a successful catheter ablation as defined as being clinically free of AF 1 year after the procedure without the use of antiarrhythmic drugs. An average of 3.1 years following the last ablation, 186 of the patients underwent 7-day event monitoring. The remaining 17 patients had pacemakers, the records of which were analyzed for the most recent year.

The 7-day event monitoring showed that 95.7% of the patients had no AF recurrence at all. Amongst the 8 patients with recurrence, 1 was found to have persistent AF. For the other 7, AF burden varied between 0.0075% (45 seconds/week) and 3.34% (5.6 hours/week) with 3 patients out of 7 having a burden of 0.037% (4 minutes or less/week). In the pacemaker group, 76.5% were totally AF-free during the 1-year analysis period. The AF burden amongst the 4 patients with recurrence ranged from 0.0037% (22 seconds/week) to 0.16% (16 minutes/week).

The authors conclude that the AF burden (silent and symptomatic) experienced 3 years post-ablation by patients whose last ablation was clinically successful at 1-year post-ablation is very low. They suggest that an AF burden of more than 0.5% on long-term monitoring may be a more realistic definition of ablation failure than a single arrhythmia recurrence lasting longer than 30 seconds. They also noted that the only variable directly correlated with ablation failure was AF duration. In other words, the longer a patient had suffered from AF prior to the ablation, the greater the chance of failure.
Winkle, RA, et al. Atrial arrhythmia burden on long-term monitoring in asymptomatic patients late after atrial fibrillation ablation. American Journal of Cardiology, May 31, 2012 [Epub ahead of print]

Editor’s comment: I wholeheartedly concur with the above conclusion. To suggest that one 31-second arrhythmia episode, following a suitable blanking period, would classify an ablation as a failure is just not realistic in the real world. Most afibbers who have suffered frequent and/or protracted symptomatic episodes prior to their ablation would not consider it a failure, even if they should experience a few short episodes lasting longer than 30 seconds. NOTE: Only 2% of the 203 patients involved in the study actually had an AF burden exceeding 0.5% (50 minutes/week) on long-term monitoring.