Left atrial function following repeat ablations
BARCELONA, SPAIN. A radiofrequency catheter ablation for atrial fibrillation (AF) creates a significant amount of scar tissue. An important question is does this scar tissue impair the function of the left atrium? Although the function of the left atrium is mainly to act as a reservoir for the left ventricle, it does contribute some pumping action on its own and a significant reduction in this action may have undesirable consequences. Prior research has shown that the volume of the left atrium tends to shrink after a first ablation (a beneficial effect) and that the contractile function is not impaired. NOTE: Contractile function is assessed as the active emptying percentage of the total left atrial volume.

Electrophysiologists at the University of Barcelona now confirm the above findings. Their study included 154 patients with symptomatic, drug-refractory AF. The majority (78%) of the patients were men, average age was 53 years, and average time since diagnosis was 5 years. Half of the study participants had paroxysmal AF, 36% had persistent AF, while the remaining 14% had been in AF for more than a year (permanent AF). Prior to their scheduled ablation and 6 months post-ablation, all patients had their left atrial volume and active emptying percentage measured using real-time, 3-dimensional echocardiography.

All patients underwent an anatomically-guided (CARTO) pulmonary vein isolation procedure with an additional left atrial roof line in the case of persistent and permanent afibbers. Patients were followed at 1, 3 and 6 months to evaluate recurrence. At the 6-month follow-up, 54% of patients having undergone a single procedure were in normal sinus rhythm (NSR), while only 40% of the 50 patients who underwent a second procedure were in NSR. Patients in the single ablation group who experienced recurrence after 6 months (mostly persistent afibbers) had a significantly larger left atrial volume prior to their ablation than did those who were in NSR at 6 months post-ablation.

Maximum left atrial volume was reduced from a baseline average of 60 to 52 mL and a minimum volume from 38 to 32 mL after a first ablation. Reductions after a second procedure were from 57 to 52 mL (maximum volume) and from 37 to 35 mL (minimum volume). Contractile function (active emptying percentage) did not change significantly (39% vs 43%) after a first or second procedure (36% vs 36%). The Spanish researchers conclude that the contractile function of the left atrium is not deleteriously affected even after repeat ablations, and that radiofrequency catheter ablations result in a beneficial shrinking of the left atrium.

Montserrat, S, Brugada, J, et al. Effect of repeated radiofrequency catheter ablation on left atrial function for the treatment of atrial fibrillation. American Journal of Cardiology, Sept. 8, 2011 [Epub ahead of print]

Editor's comment: Many afibbers have expressed concern about the effect of one or more radiofrequency ablations on the function of the left atrium. This study provides reassuring proof that such concerns are unwarranted.