TURIN, ITALY. Electrophysiologists have placed a great deal of emphasis on establishing the factors determining the long-term outcome of catheter ablation for atrial fibrillation (AF). It is generally accepted that achieving a successful outcome is more challenging when it comes to persistent and permanent AF than in the case of paroxysmal AF. Some studies have also found an enlarged left atrium to be detrimental to success, and a recent Dutch study concluded that long-duration paroxysmal episodes prior to the first ablation are associated with a poorer outcome. Now an international group of researchers with participants from Italy, United Kingdom, China, Japan, Taiwan, and the USA reports on a meta-analysis of 19 studies aimed at determining factors affecting mid-term success and procedural complications.

The analysis included 7200 patients and over 9000 procedures. The majority (60%) had paroxysmal AF, 15% had persistent, and 25% had permanent AF. The average age of the patients was 57 years and 77% were male. Fifteen percent of patients had a history of heart disease or heart failure, 44% had hypertension, and the average left atrial diameter was 42 mm. All patients underwent an initial pulmonary vein isolation (PVI) procedure with 27% receiving additional linear lesions and 15% having complex fractionated atrial electrograms ablated as well. After an average follow-up of 22 months and 1.23 procedures per patient, 69% of patients were in normal sinus rhythm corresponding to a recurrence rate of 31%. NOTE: It is not clear whether this number included patients still on antiarrhythmics. The recurrence rate in studies where follow-up exceeded 30 months was 34% or a 66% success rate.

Although the success rate for persistent AF was significantly lower than for paroxysmal AF, after the initial procedure there was no significant difference after redo procedure(s). The authors conclude that the following variables are detrimental to mid-term success:

• Recurrence of AF within 30 days after ablation;
• Valvular atrial fibrillation;
• Left atrial diameter in excess of 50 mm.

In-hospital complication rates associated with the 9000 procedures were low with tamponade requiring drainage occurring in 0.99% of cases, strokes/TIAs with no after-effects occurring in 0.36%, and stroke with persistent impairment occurring in 0.22% of cases.
D'Ascenzo, F, et al. Which are the most reliable predictors of recurrence of atrial fibrillation after transcatheter ablation? International Journal of Cardiology, May 22, 2012 [Epub ahead of print]

Editor's comment: This study adds to previous data showing that the following variables are important predictors of a negative ablation outcome:

• Longer duration of paroxysmal episodes;
• Recurrence within 30 days of ablation;
• Valvular atrial fibrillation;
• Left atrial diameter in excess of 50 mm;
• Need for cardioversion during procedure;
• An elevated level of C-reactive protein prior to procedure;
• Having experienced no benefit from antiarrhythmic drugs;
• Low left ventricular ejection fraction;
• Enduing AF for too long before having an ablation.

Although recurrence within 30 days of ablation does increase the risk of recurrence, it is by no means an absolute indication of failure.