SAN DIEGO, CALIFORNIA. Most afibbers who have undergone a successful pulmonary vein isolation (PVI) procedure for atrial fibrillation sometimes wonder if the cure is truly permanent or "the beast" will eventually return. It is only about 10 years ago that Professor Michel Haissaguerre and colleagues at the Hopital Cardiologique du Haut Leveque in Bordeaux discovered that the vast majority of paroxysmal afib episodes originate in the pulmonary veins and that isolating the veins electrically from the left atrium can eliminate AF. Thus, very little data is actually available as to the long-term results of a successful PVI.
Electrophysiologists at the University of California (San Diego) now partially fill in this gap in our knowledge by reporting 5-year follow-up results for 71 paroxysmal, symptomatic afibbers (average age of 60 years with 79% being male) who underwent a segmental antrum PVI procedure (Natale protocol) between January 1, 2002 and August 31, 2003. Only 10% of the patients had structural heart disease, so 90% would be classified as lone afibbers, although 37% did have hypertension. The PVIs were performed using an 8-mm non-irrigated ablation catheter guided by ICE (intracardiac echocardiography) and fluoroscopy with some later procedures also using electroanatomical (NavX) guidance. The goal was to fully isolate all pulmonary veins, but in 33 patients (46%) the right lower PV could not be fully isolated.
The patients were followed for a minimum of 5 years with clinical visits 1, 3, 6 and 12 months post-ablation and then at 6- to 12-month intervals. All clinic visits included a 12-lead electrocardiogram and patient input regarding recurrence of symptomatic episodes. At the 1-year follow-up 61 patients (86%) were free from symptomatic afib and off all antiarrhythmics. After 2 years, 79% were still in normal sinus rhythm, but at the 5-year check-up only 56% remained free of symptomatic afib. The 31 study participants (44%) whose PVI had failed within the 5 years underwent one or more repeat ablations of which 58% were successful.
Thus, at the end of 5 years, after an average of 1.6 procedures, 82% of the original 71 participants were in normal sinus rhythm without the use of antiarrhythmics. However, the mean duration of follow-up for the 31 patients who underwent one or more follow-up procedures was only 13 months. The researchers observed that all repeat ablations involved re-isolating parts of the lesion rings around the pulmonary veins where electrical conduction had been re-established between the veins and the left atrium. They also noted that patients with hypertension were significantly more likely to need a re-ablation than were those with normal blood pressure.
Sawhney, N, et al. Five-year outcomes after segmental pulmonary vein isolation for paroxysmal atrial fibrillation. American Journal of Cardiology, Vol. 104, 2009, pp. 366-72
Editor's comment: It is discouraging to see that there is only about a 56% chance that a single PVI will keep one in NSR for 5 years or more. However, in considering these results a little closer, it should be kept in mind that all the PVI failures involved re-establishment of electrical connection between the pulmonary veins and the left atrium. Whether or not such reconnection occurs is very closely tied in with operator skill in ensuring transmurality of the lesion; in other words, making the lesion deep enough to prevent conduction, but not so deep that the heart wall is penetrated (cardiac tamponade). It is also likely that an irrigated catheter would produce longer-lasting lesions. So overall, it would seem that the number of ablatees who can expect to remain afib-free for 5 years or longer is bound to increase significantly as operator skills and techniques improve.