Long-term ablation outcomes in Australia

MELBOURNE, AUSTRALIA. A fortunate trend seems to be emerging, namely that of reporting long-term outcomes of catheter ablation. The Bordeaux group (Profs. Haissaguerre and Jais at Hopital Cardiologique du Haut-Leveque) recently reported a 5-year AF-free survival rate of 63% in a group of 100 patients with paroxysmal (64%), persistent (22%) or permanent (14%) atrial fibrillation.

Now electrophysiologists at the Royal Melbourne Hospital report their results for a group of 100 consecutive patients with highly symptomatic paroxysmal atrial fibrillation (AF) who had undergone one or more circumferential pulmonary vein antral isolation (PVAI) procedures. The average age of the patients was 54 years (44 to 64 years) and 79% were men. None had structural heart disease, but 27% had hypertension and 6% had coronary artery disease. The average duration of AF was six years.

Interestingly enough, the Australian researchers also report on the episode frequency and severity prior to ablation. A total of 34% of the study participants experienced AF episodes at least once a week, 27% had at least one episode a month, and the remaining 39% went more than a month between episodes. The episode duration was commonly between 1 and 24 hours (76%), but 10% reported episode duration of less than an hour and 14% reported duration of more than 24 hours. A severity score was also developed with scores from 1 to 10 with 10 indicating more severe symptoms. A composite score of episode frequency, duration and severity was also developed (ranging from 3 to 30) and named “Total AF Burden Score”.

All patients underwent a PVAI using a combination of electrophysiological and anatomical guidance and employing a radiofrequency-powered 4 mm irrigated catheter. The endpoint of the procedure was electrical isolation (from the left atrium) of all four pulmonary veins through the placement of two wide circular lesions of ipsilateral veins. The procedure was performed under general anaesthesia and was free of major complications. Patients were followed up at 3, 6, 9 and 12 months and then at least every six months thereafter. Holter monitoring or 7-day monitoring was also performed at any hint of symptoms of possible recurrence.

After an average follow-up of 39 months since the initial PVAI, 49% of patients were in normal sinus rhythm without the use of antiarrhythmics. Twenty-two patients underwent a repeat procedure during which it was found that all had recurrent conduction across previously isolated pulmonary vein–left atrium junctions. After an average 1.2 procedures, 57% of patients were in sinus rhythm after 39 months, while another 25% were in sinus rhythm aided by previously ineffective antiarrhythmics. Thirteen patients continued to have paroxysmal episodes, but their Total AF Burden Score declined from an average of 17 to 10. Thirty-seven patients experienced at least one episode of AF or atrial tachycardia after a 1-month blanking period, and 86% of these patients developed recurrent arrhythmia within 12 months of their procedure. In contrast, only 14% of patients had recurrence after having been AF-free for 12 months or more. Kaplan-Meyer curves predicted freedom from AF (no AF with or without antiarrhythmics) after the final procedure of 87% at 12 months post-PVAI and 80% at 4 years post-PVAI.

The researchers conclude that the majority of patients who are free of AF at 1-year post-ablation can be reassured that the risk of later recurrence is relatively small, although antiarrhythmics may be required to maintain normal sinus rhythm.

Medi, C, et al. Pulmonary vein antral isolation for paroxysmal atrial fibrillation: results from long-term follow-up. Journal of Cardiovascular Electrophysiology, August 31, 2010 [Epub ahead of print]

Editor’s comment: It is of interest to compare some of the Australian findings to those reported in our 2009 Ablation/Maze Survey. The Australian researchers reported that 57% of patients were in sinus rhythm without the use of antiarrhythmics at the 3-year mark (39 months). Another 25% were AF-free with the use of antiarrhythmics. In our survey 69% were in sinus rhythm in year 3-4 without the use of antiarrhythmics, while another 6% were AF-free with the aid of antiarrhythmics. As found in the Australian study, the major determinant of an AF-free existence at 3 years was the absence of AF at 12 months post-ablation. In our survey, absence of AF at 12 months post-ablation was associated with an 80% complete success rate and a partial success rate of 4% at year 3-4. Having experienced episodes during the last 6 months of the 12-month period following the procedure was associated with a 29% complete success rate and a 12% partial success rate. This is a clear vindication of the conclusion that AF-free status during the first year post-ablation (excluding a suitable blanking period) is crucial for long-term success.