Atrial Fibrillation Ablation - Are we ready?

Atrial fibrillation (AF) is the most common arrhythmia in day to day practice. It contributes to morbidity in the form of heart failure and stroke and increased overall and cardiovascular mortality1. Moreover, no treatment of AF to date has resulted in a lower overall death rate. Anti arrhythmic therapy for AF may also contribute to increased mortality in this subgroup2. Even though AFFIRM investigators showed no apparent benefit from rhythm control, these results cannot be generalized to younger patients, more symptomatic patients and those with rheumatic valvular disease. Catheter ablation for the same seems to be an attractive approach. Catheter ablation for AF is an evolving field. In the late 1990s, a group in Bordeaux demonstrated that the muscle sleeves that surround the pulmonary veins can be very arrhythmogenic and very often supply the triggers that set off atrial fibrillation. This resulted in opening up of new therapeutic avenue that is isolation of the pulmonary veins. Various techniques were described for the same like linear, focal ablation, PV isolation and circumferential antral ablation. Early linear ablation was an empirical version of a "catheter maze," initially limited to the right atrium. With the identification of PV foci, attention was soon directed at these specific targets. Initial ablations have been without 3 D mapping with use of Lasso or similar catheters. With continuous evolution of 3 D mapping techniques, circumferential antral ablation remains the most common technique used at this time. Variations of it like Wide Area Circumferential Ablation (WACA) or Left Atrial Catheter Ablation (LACA) and Pulmonary Vein Antrum Ablation/Isolation (PVAI) have resulted in better overall outcomes. Till date, however, there has been no standardization of the technique. Even though there is a trend towards better initial success, 6 month cure rates with new ablative techniques are still inferior to surgical results. Fisher et al3 in reviewed all publications through 2005 if data included information on technique and 6 month follow up. More than 23000 subjects met the criteria. Cure rate with PVAI was 67 % at 6 months. 25% patients required repeat procedures. They observed trend towards inclusion of patients with permanent and persistent AF with improvement in the various mapping and ablative techniques. Although there is trend towards reduced fluoroscopy times, still it remains high, i.e. 201 min for PVAI. Complication rates remain high like stroke, repeat procedures, PV stenosis and catastrophic atrio-esophageal fistulae represent real limitation of AF ablative procedures. An atrio-esophageal fistula is a relatively recently recognized complication. Radiofrequency line on the posterior wall of LA can result in thermal injury to the esophagus, as the LA posterior wall is relatively thin measuring about 1.72 mms, whereas radiofrequency ablation can cause 45 mm