Results.
A total of 76 consecutive patients with symptomatic, drug refractory paroxysmal AF were enrolled. The study group included 34 patients undergoing WACA and 32 patients undergoing WACA+. Finally, 10 patients underwent a staged procedure of WACA that was followed by WACA+ in case of lack of first pass isolation with WACA only (Table 1). Procedural time, dwell time, fluoroscopy time and radiofrequency time were not different between the study (WACA and WACA+) groups (Table 2).
In contrast to a WACA only approach, the WACA+ approach (of systematically performing ablation of the carina in addition to WACA) increased the odds of achieving PV isolation from 65% (22 of 34 in the WACA group) to 91% (29 of 32 in the WACA+ group, p=0.012). Analysis of patients not achieving first pass PV isolation further demonstrated the crucial role of the carina. In the WACA-only group, first pass isolation was not achieved in 12 patients: in 7 patients (representing 20% of the WACA group and 58% of the WACA not achieving first pass PV isolation), the right carina had to be ablated to achieve right sided veins isolation; in 3 patients, the left carina had to be ablated to achieve left sided veins isolation; finally, in 2 (6.7 %) patients both carinas had to be ablated to achieve pulmonary veins isolation.
In the WACA+ group, first pass isolation confirmed with circular mapping catheter was achieved in 29 (91%) of patients. Two patients (9%) required additional ablations to achieve isolation. In the first, this was delivered at the anterior ridge where the previous ablation reached an ablation index value of 480, while in the second additional ablation was required at the anterior carina.
Based on the results of the study group (WACA and WACA+ groups) pointing out at the carina as a critical site that needs to be ablated to achieve complete PV isolation, we added a small third group of 10 patients who underwent a step-by-step ablation of WACA and carina. In group 3, before the carina was ablated, first pass isolation was achieved in 2 patients (20%) patients only. In all patients the lack of isolation and its location demonstrated with the ablation catheter was confirmed with the circular mapping catheter. In the remaining 8 patients, the left carina, the right carina and both carina areas, had to be ablated to achieve PV isolation in 4 (40%), 2 (20%) and 2 (20%) patients, respectively.
Adenosine challenge revealed dormant PV-LA connections in 5/34 (14.7%) in the WACA group, 4/32 (12.5%) in the WACA+ patients and 1/10 (10%) in group 3 (p=NS). In 4 of 5 patients with dormant PV-LA connection revealed by adenosine in group 1, the dormant connection was detected in the 3 at the left carina, in 1 in the right carina and in 1 at the anterior ridge. In group 2, the dormant connections were detected at the left carina and the right carina in 2 patients each. In group 3 dormant connection was detected at the left carina.
At the procedure termination, acute pulmonary vein isolation was achieved in 100% of pulmonary veins ablated in the three groups.
No major complications occurred in any of the patients enrolled.
At a mean follow up of 18 months [IQR 15.2-20.8], freedom from atrial fibrillation was 84% for the entire cohort. In group 1 the success rate was 76.5% (26/34). In group 2 the success rate was 87.5% (28/32), (p=0.342). In group 3 the success rate was 90% (9/10). In view of the small number of patients, the success rate of group 3 was not compared to that of group 1 and 2.