BARCELONA, SPAIN. Many afibbers, myself included, have wondered just how efficient the pumping action of the left atrium is after undergoing an extensive RF ablation. Researchers at the University of Barcelona obviously wondered about this too and now report on a clinical trial to find the answer. They measured the left atrial ejection fraction (LA EF%) using cardiac magnetic resonance imaging (MRI) in 55 patients (in normal sinus rhythm) who had undergone one or more circumferential pulmonary vein ablations for paroxysmal or persistent AF. The researchers defined LA EP% as (LAmax – LAmin/LAmax) x 100 where LAmax is the volume of the left atrium immediately before the mitral valve opens to allow blood flow into the left ventricle, and LAmin is the volume immediately after closure of the mitral valve.

MRI was performed prior to the ablation and 4-6 months following the ablation. After an average of 1.2 ablations, 60% of the patients were in normal sinus rhythm (NSR) without the use of antiarrhythmics, 9% were in NSR with the use of antiarrhythmics, and the remaining 31% were still experiencing episodes. Patients were prescribed an antiarrhythmic for the first 4 weeks following the procedure and remained on warfarin for a minimum of 2 months post-procedure.

The researchers found that the LA EF% increased or remained stable in 68% of the patients whose ablation had been successful (with or without antiarrhythmics). In contrast, patients whose ablation had not been successful experienced an average drop of 11% in their LA EF%, indicating that the contractibility of the left atrium had been impaired by the unsuccessful ablation. The decline in LA EF% was associated with a smaller decrease in LAmin after the ablation among patients with an unsuccessful procedure than among those with a successful one. The contractibility of the left atrial appendage was not affected by the ablation irrespective of outcome.

Perea, RJ, et al. Left atrial contractibility is preserved after successful circumferential pulmonary vein ablation in patients with atrial fibrillation. Journal of Cardiovascular Electrophysiology, Vol. 19, April 2008, pp. 374-79

Editor's comment: It is indeed comforting to know that the pumping action of the left atrium and the left atrial appendage is not likely to be impaired following a successful RF ablation.