BORDEAUX, FRANCE. In this article persistent atrial fibrillation (AF) is defined as AF lasting more than 7 days or lasting less than 7 days, but necessitating pharmacological or electrical cardioversion. Thus, permanent afib would appear to be included in this definition. It has long been known that persistent and permanent afib are far more difficult to cure with catheter ablation than is paroxysmal (intermittent) AF. While paroxysmal AF can often be cured by isolation of the pulmonary veins alone, the successful treatment of persistent/permanent AF requires the application of other lesions in the left atrium. It is now also clear that even a successful AF ablation is often followed by the development of atrial tachycardia (regular pulse rate in excess of 100 bpm).
Electrophysiologists at the Hopital Cardiologique du Haut Leveque recently concluded a clinical trial to determine the incidence of and the effect of additional lesions on post-procedure atrial tachycardia (AT) in a group of 180 patients with persistent AF. A comprehensive ablation procedure involving segmental pulmonary vein ablation (PVI), electrogram-based ablation plus left atrial roof and/or mitral isthmus lines terminated AF in 154 patients, while the remaining 26 patients (14%) had to continue on antiarrhythmics. Among the 154 patients, 76% were men and they had suffered from persistent AF for an average of 5 years. Forty-five percent had structural heart disease and 14% had heart failure at the time of the procedure. Average left ventricular ejection fraction in the group was 57% and left atrial diameter (antero-posterior) ranged from 44 to 51 mm.
The 154 patients in which AF had been terminated were divided into two groups. Group A (55% of patients) consisted of those who had not required both roof and mitral lines in order to terminate the AF, while group B (45% of patients) consisted of those who had required both lines. Immediately following the procedure, 62% of group A developed AT as opposed to only 35% in group B. During a 28-month follow-up, 43% of patients developed AT recurrence and underwent re-ablation since this new rhythm disturbance was resistant to both antiarrhythmics and repeated cardioversion.
Ultimately, 82% of the 154 patients required both a mitral line and a roof line, 14% required the roof line only, 2% required the mitral line only, and 2% required no left atrium linear ablations. In group A, 76% required an additional linear lesion for AT either acutely or within the follow-up period. The corresponding number for group B was only 35%. The Bordeaux researchers conclude that, while it may be possible to terminate AF by catheter ablation without linear lesions, the majority of patients will ultimately require linear lesions for subsequently occurring macro re-entrant AT.
Knecht, S, et al. Left atrial linear lesions are required for successful treatment of persistent atrial fibrillation. European Heart Journal, Vol. 29, 2008, pp. 2359-66
Rostock, T and Willems, S. Rhythm-'a-line-ment' during catheter ablation of chronic atrial fibrillation. European Heart Journal, Vol. 29, 2008, pp. 2321-22
Editor's comment: Many afibbers with persistent/permanent afib have experienced in some cases very severe atrial tachycardia following an otherwise successful procedure for atrial fibrillation. The study by the Bordeaux researchers makes it clear that post-procedural AT is indeed very common and may ultimately require extensive linear ablation lines to overcome – one more reason for persistent/permanent afibbers to choose only the most experienced EP to perform the procedure.