Ablation:
Ablation was performed using a “point by point” technique. Settings were: catheter irrigation-flow rate of 18 mL/min, target temperature 45° and maximal energy of 50 W. During the ablation we aimed to achieve a contact force of 10 to 20 grams at all times. Radiofrequency energy (RF) was applied at each ablation site using the automated lesion tagging ablation-index module (Biosense Webster) to mark the location and efficacy of each lesion. The ablation-index settings were: catheter stability position minimum-time of 5 seconds, and maximum range 3-4 mm, minimum force 3 g, (the blue and yellow marks give two different contact force values) and lesion tag of 3 mm. The maximal RF time at each ablation site was 10 seconds for the posterior wall and 25 seconds for the anterior quadrants. We aimed for an ablation-index value of 400 for the back wall and 500 for the anterior quadrants. Upon completion of the wide antral circumferential ablation (WACA), the ablation catheter was withdrawn from the left atrium and replaced by a lasso circular mapping catheter (Lasso, Biosense Webster, Inc). The acute end-point of the procedure was PV isolation demonstrated by disappearance of local PV electrograms and confirmed by standard pacing maneuvers, to confirm entrance and exit block, with a lasso circular mapping catheter. In case of lack of first pass isolation the residual PV-LA connections were tagged on the CARTO system and additional RF was delivered until PV isolation was achieved. After a waiting period of 20 minutes, each pulmonary vein was assessed for entrance and exit block. Each vein was also assessed for the presence of dormant pulmonary vein-left atrium connection with intravenous adenosine 18 mg injection. Patients with evidence of dormant connections revealed by adenosine challenge, received additional ablations according to the mapping catheter until the connections were completely abolished.