Flutter ablation and PVI – Not enough?
MAASTRICHT, THE NETHERLANDS. Right atrial flutter (AFL) and atrial fibrillation (AF) often coexist. Some cardiologists and electrophysiologists believe that it is possible to eliminate the AF component by performing a cavotricuspid isthmus ablation (right atrial flutter ablation) only and thus avoiding going into the left atrium. Our ablation/maze surveys have consistently shown that this approach is unlikely to be successful and that 90 to 95% of afibbers still experience episodes even after a successful flutter ablation.

A team of Dutch EPs now report that even doing a standard PVI in combination with the flutter ablation is unlikely to eliminate the AF. Their clinical trial involved 36 patients with AF and at least one documented episode of sustained common-type AFL (group 1) and 62 patients with just paroxysmal AF (group 2). The average age of the patients was 50 years, 78% were lone afibbers, and 24% were women. Group 1 underwent a standard flutter ablation followed by a 6-week monitoring period and a subsequent PVI (without any additional lesions). Group 2 patients underwent a standard PVI with no additional lesions. All procedures were performed using a cryoablation catheter (CryoCor Inc, San Diego, CA) and a duodecapolar LASSO catheter for mapping (segmental PVI).

The number of afib episodes among group 1 members was not reduced during the 6 weeks following the flutter ablation indicating, as expected, that a flutter ablation, on its own, is likely to be unsuccessful in eliminating coexistent AF. Group 1 members then underwent a PVI (cryoablation) without additional lesions. After a 3-month blanking period, the patients were followed for a further 2 years (on average). During this period, 67% experienced recurrent AF and 14% experienced recurrent atrial flutter, which was successfully eliminated with a second flutter ablation. Among the 24 patients who had recurrences of AF, 6 underwent a successful second PVI and 17 improved through the use of antiarrhythmic medications. Thus, the complete success rate in this group was 25%. In the group that underwent a second flutter ablation, 3 eventually became free of any arrhythmia, so taking group 1 as a whole the complete success rate was 31%.

During the 2-year follow-up after the 3 months blanking period, 7 patients (11%) in group 2 experienced recurrent AF, while 5 patients (8%) experienced new onset atrial flutter. The 7 patients experiencing AF breakthroughs underwent a repeat PVI after which 5 were afib-free with no drugs, and 2 were improved but still on antiarrhythmics. The 5 patients with atrial flutter underwent a right atrial flutter cryoablation after which 2 became asymptomatic, and 1 improved on antiarrhythmics. Thus, the final complete success rate in group 2 was 89%, the partial success rate (improved, but still on antiarrhythmics) 5%, and the failure rate 6%.

The authors conclude that right atrial flutter ablations, on their own, are insufficient to eliminate paroxysmal AF in patients who suffer from coexistent AF and flutter. Even adding a standard PVI (with no additional lesions) only brings the success rate to 31%. In contrast, a PVI with no additional lesions (repeated as necessary) has a complete success rate of 89% in patients with paroxysmal AF only. This could indicate that in patients with both atrial flutter and AF non-pulmonary vein triggers are the culprit behind AF or that sufficient electrical remodeling has already occurred in both atria, and thus a strategy that includes substrate modification may be required.

The authors also suggest that it is not necessary to do a routine flutter ablation as part of the PVI procedure in patients who only have paroxysmal AF since the post-procedure development of atrial flutter in this group is only 8%.

Moreira, W, et al. Can common-type atrial flutter be a sign of an arrhythmogenic substrate in paroxysmal atrial fibrillation? Circulation, Vol. 116, December 11, 2007, pp. 2786-92
Waldo, AL. Atrial fibrillation – atrial flutter interactions. Circulation, Vol. 116, December 11, 2007, pp. 2774-75

Editor's comment: This clinical trial confirms our survey findings that a right atrial flutter ablation, on its own, is unlikely to cure AF in patients suffering from coexistent AF and flutter. It also reveals that, even if the flutter ablation is combined with a PVI, without looking for triggers outside the pulmonary veins, it is unlikely to cure AF in patients suffering from coexistent AF and flutter. Thus, afibbers with coexisting AF and flutter should make extra sure that they go to the very best EP for their procedure since it will involve more than just a simple isolation of the pulmonary veins.