ATHENS, GREECE. Pulmonary vein isolation (PVI) is now a well-established procedure for "curing" atrial fibrillation. Acute success rates (elimination of electrical potentials between pulmonary veins and the left atrium), measured shortly after lesion completion, are indeed impressive and often quoted as between 90 and 100%. Unfortunately, this does not mean that 90-100% of afibbers undergoing a PVI are free of afib for the remainder of their life, or even for the first 6 months after the procedure. A team of American and Greek researchers now provide the first evidence that long-term (over 3 years) success rates are substantially less than generally believed.

Their study involved 39 patients (average age of 52 years, 87% male) with symptomatic paroxysmal atrial fibrillation (about 30% with LAF and 50% with hypertension). All patients underwent a first segmental PVI (antral in 4 cases) and were then followed for an average 3.5 years (minimum of 3 years). Total pulmonary vein isolation was verified in all cases before catheter withdrawal. During the follow-up, the team made the following observations:

• Ninety-two percent of all patients experienced at least one AF recurrence within 3 to 42 months of the initial procedure (first 2 months were considered a blanking period); 22% of these episodes were within the third month, 22% between months 3 and 12, and the remaining 56% occurred more than 12 months after the first procedure. This equates to a complete long-term success rate of 8% after just one ablation.
• Twenty-five of the 36 patients with recurrence (69%) underwent a second ablation. Among these, 10 patients (40%) experienced no relapse, while the remaining 15 (60%) were either classified as failures (60%), or went on to undergo a third ablation which was successful in 67% of cases. (NOTE: 80% of patients undergoing the third ablation had the circumferential procedure).
• Overall, the long-term (longer than 3 years) success rates were 21.4% for patients undergoing just one procedure, 52.6% for those undergoing two, and 66.7% for those who underwent 3 procedures. However, symptomatic improvement was reported in 67% of all patients.

The team concludes that, 3.5 years (on average, but minimum 3 years) after the initial procedure, 46% of study participants were free of afib, while 67% experienced symptomatic improvement. To accomplish this, almost half of the patients had a second procedure, and 15% underwent a third.

Katritsis, D, et al. Long-term follow-up after radiofrequency catheter ablation for atrial fibrillation. Europace, Vol. 10, 2008, pp. 419-24

Editor's comment: The long-term success rates found in this study are indeed sobering. It should be kept in mind though that the ablations were not performed at top-ranked institutions where success rates would be expected to be significantly higher. Nevertheless, the study clearly shows that follow-up ablations may be the norm rather that the exception, and also makes it abundantly clear that acute success is in no way related to long-term success.