BORDEAUX, FRANCE. Although there is ample evidence that catheter ablation can be highly effective in eliminating atrial fibrillation (AF) in the short term, there is, except for our 2009 Ablation/Maze Survey, no published data regarding the long term durability of the procedure. Electrophysiologists at the Hopital Cardiologique du Haut-Leveque have now remedied this shortcoming. Their study involved 100 patients resident in France who underwent catheter ablation for AF during the period January 2001 to April 2002. During these early years of pulmonary vein isolation procedures (PVIs), the Bordeaux group was already performing an average of two procedures five days a week.
The patients involved in the study were predominantly male (86%) with an average age of 56 years and the average length of time they had suffered from AF was six years. Most (64%) had paroxysmal AF, 22% had persistent AF, and the remaining 14% were in permanent AF (long-standing persistent). None of the patients had undergone prior ablation or surgery to deal with their condition, and all experienced at least one hour a week (average) of AF.
The patients all underwent an initial segmental PVI procedure as well as cavotricuspid isthmus ablation (ablation for right atrial flutter). Seventy-five per cent also had linear ablation (left isthmus and/or roofline) during the first procedure. During the first six months following the procedure, about 50% of the patients had at least one arrhythmia episode – defined as an AF, flutter or tachycardia episode lasting 30 seconds or longer. Arrhythmia-free survival rates (from Kaplan-Meyer curves) after a single procedure were 40% at the end of the first year, 37% at the end of the second year, and 29% at the end of the fifth year.
Fifty-one patients underwent one or more repeat procedures to reconnect gaps that had appeared in pulmonary veins or linear lesions. Afib-free survival one year after the final procedure was 87% and 81% and 63% respectively at two and five years after a median of two procedures. The major predictors of arrhythmia recurrence were permanent AF (odds ratio of 2.6), valvular heart disease (odds ratio of 5.2), and non-ischemic dilated cardiomyopathy (odds ratio of 34.0). Thus, it seems likely that an otherwise healthy paroxysmal afibber could expect a significantly better long-term, afib-free survival rate than indicated by the figures presented above.
The authors of the study make the interesting observation that none of the patients with paroxysmal AF at the start of the study progressed to persistent or permanent AF during the follow-up, and also emphasize that there were no procedure-related deaths.
Weerasooriya, R, et al. Catheter ablation for atrial fibrillation: are results maintained at 5 years of follow-up? Journal of the American College of Cardiology, Vol. 57, No. 2, January 11, 2011, pp. 160-66
Editor's comment: The Bordeaux study is a most welcome addition to our sparse data and evidence concerning the longevity of a catheter ablation for the purpose of curing AF. The quoted rates for afib-free survival does, however, in my opinion, paint a too pessimistic picture of single procedure success rates. It is well known that atrial arrhythmias are common during the first six months following a catheter ablation and indeed in this study, 56% of participants reported arrhythmias lasting more than 30 seconds during this period. These patients were presumably counted as failures, thus resulting in arrhythmia-free survival rates as low as 40%, 37% and 29% after one, two and five years. The success rates would obviously have been substantially higher if the first six months had been counted as a blanking period rather than as part of the follow-up.
Our 2009 Ablation/Maze Survey involved 88 AF patients who had undergone their last catheter ablation more than four years ago (53 had only one procedure). The long-term success rate (no atrial arrhythmia and no use of antiarrhythmic drugs) was found to be highly dependent on whether or not the patients had experienced atrial arrhythmias during the last six months of the 12-month period following their last procedure (Index Period). Those who had not experienced arrhythmias during their index period had success rates of 84% at year two, and 86% at year five. In contrast, those patients who did experience arrhythmias during the index period had success rates of only 33% at years two and five. Thus, absence of atrial arrhythmias during the index period is clearly a very important predictor of long-term success. Being a persistent or permanent afibber prior to the procedure was found to be associated with a 5% lower success rate at five years (87% for paroxysmal and 82% for persistent and permanent).
In judging the long-term success of catheter ablation for AF, it should also be kept in mind that the failure criteria of one episode lasting 30 seconds or more, is very strict and not really that relevant to an individual AF patient. In our survey we found that at the end of year four, 27% of respondents were still experiencing AF episodes. However, their frequency was down by 95% from pre-procedure levels and the total time spent in AF was down from 7% to 0.2% for paroxysmal afibbers. The reduction in AF burden from pre-procedure days to year four was 97%, and this decline was pretty well universal with only 1 in 16 respondents reporting an increase in burden.