Presenting the findings at the American Heart Association 2006 Scientific Sessions last week, lead investigator Dr Arti Shah (St Luke's-Roosevelt Hospital Center, New York, NY) showed that in a cohort of patients free from atrial fibrillation at one year, symptomatic atrial fibrillation recurred in 8.7%, with the attrition rate beginning approximately two years after the initially successful ablation.

Presenting the study, Shah explained that although a large population of patients who undergo pulmonary-vein isolation for atrial fibrillation have a complete response to therapy and are free of the arrhythmia, it is unclear whether these patients are cured or whether there is a late attrition rate. To examine the possibility of late recurrence, investigators studied patients free from atrial fibrillation at one year, all of whom discontinued drug therapy at one month. Patients, the majority of whom were male (72%) and had paroxysmal atrial fibrillation (82%), were then followed for one to five years.

All pulmonary-vein-isolation ablations were electrophysiology guided using a lasso catheter, and the aim of procedure was complete electrical disconnection. If a repeat ablation was needed three to six months after the initial ablation, the pulmonary veins were reisolated and additional left atrial and mitral isthmus lesion sets were performed as necessary. Overall, 264 patients were free from atrial fibrillation at one year. Of these patients, 233 were free of the arrhythmia after the first ablation and 31 were free from atrial fibrillation after a follow-up ablation procedure performed within three to six months.

Of the 264 patients, symptomatic recurrence was observed in 23 patients free from atrial fibrillation at one year, occurring approximately two years after the initial ablation procedure. Most late recurrences were associated with a pulmonary vein-left atrial reconnection, noted Shah.

Overall, there were no significant baseline differences, such as age, sex, type and duration of atrial fibrillation, duration of procedure, left ventricular ejection fraction, or presence of coronary artery disease, among long-term responders to ablation and those who developed late-recurrence atrial fibrillation. The presence of hypertension and hyperlipidemia, however, did predispose to late atrial-fibrillation recurrence, said Shah.

"An important recurrence rate of atrial fibrillation appeared late after successful ablation, despite more than one year free from atrial fibrillation, although a majority of patients remain atrial-fibrillation free," said Shah. "These observations stress the importance of continued long-term follow-up and raise questions regarding the need for chronic anticoagulation despite an apparent response to ablation therapy."