Real AF burden following ablation
HAMBURG, GERMANY. Routine follow-up following a catheter ablation for atrial fibrillation (AF) is usually based on periodic ECGs, 24-hour Holter monitoring, or the use of 7-day event recorders as well as on the patient's own reporting of symptomatic episodes. It is clear that these protocols could miss some episodes, especially if they are asymptomatic. A group of EPs from the University Heart Centre in Hamburg now report the results of a study to determine the "real" long-term success rate of PVIs.

The study involved 37 afibbers (20 paroxysmal and 17 persistent or permanent). The average age of the patients was 65 years, 20% were male, and 68% had no underlying structural heart disease. All study participants had previously had a pacemaker or ICD (implantable cardioverter defibrillation) implanted for sick-sinus-syndrome (53%), to prevent bradycardia when on sotalol or other drugs (16%), or because of an AV conduction block (13%). The pacemakers all had a built-in Holter monitoring function so that the researchers were able to determine, on a continuous basis, the afib burden (total time spent in afib or episode frequency multiplied by episode duration) prior to and after the ablation.

The researchers found that the mean afib burden among paroxysmal afibbers during the 7 months preceding the ablation was 17.3%; i.e. these afibbers had spent 17.3% of their lives in afib during the preceding 7 months. Among persistent and permanent afibbers, the pre-ablation afib burden averaged 57%. All participants underwent a segmental PVI and a standard right atrial flutter ablation. Additional linear lesions were created as required in persistent/permanent afibbers, two of whom underwent a follow-up procedure.

The afib burden was tabulated at 3, 6, 9 and 12 months following the procedure. Among paroxysmal afibbers, 17 patients (85%) had experienced no episodes at all during the 112-month follow-up, so had an afib burden of 0%. However, 4 of these patients were still on antiarrhythmics. The average afib burden among the remaining 3 patients had been reduced from 15.5% to 4.3%.

Among the persistent/permanent afibbers, 10 had experienced no episodes (0% post-procedure afib burden), while the remaining 7 patients had reduced their burden from an average 57.4% to 13.9%. It is of considerable interest that all Holter-recorded episodes were symptomatic and coincided fully with episodes observed by the patients themselves. NOTE: An afib episode was defined as an atrial high-frequency episode of less than 180 bpm lasting longer than 30 seconds.

Steven, D, et al. What is the real atrial fibrillation burden after catheter ablation of atrial fibrillation? European Heart Journal, Vol. 29, 2008, pp. 1037-42
Shah, D. Atrial fibrillation burden: a 'hard' indicator of therapeutic efficacy and prognostic marker to boot? European Heart Journal, Vol. 29, 2008, pp. 964-65

Editor's comment: This study confirms our survey findings that even an unsuccessful ablation usually leads to a better quality of life (reduced afib burden). However, there certainly are exceptions to this – I was one of them. Another important finding is that there were no asymptomatic episodes recorded. This demolishes the argument that life-time warfarin may still be required even after a successful PVI. Nevertheless, it should be kept in mind that all the study participants had highly symptomatic episodes prior to their ablation. If their episodes had been asymptomatic prior to the PVI, might the unlucky few still have experienced asymptomatic episodes following the procedure? The German study does not answer this question.