Radiofrequency ablation:
All index and redo PVI procedures were performed with the CARTO3 system (Johnson & Johnson, Biosense Webster). A 3.5 mm tip contact force sensing, open irrigated RF-catheter (Biosense Webster, Navistar STSF) was the ablation catheter used in all procedures. All patients underwent double transseptal puncture. An 8-Fr non-steerable long sheath was advanced in the left atrium and via the sheath a 6-Fr pigtail catheter was positioned in the center of the LA for the acquisition of the 3D-RA. A second transseptal puncture and an 8.5-Fr non-steerable sheath was advanced in the LA, housing the ablation catheter. The acquired image of the LA from the 3D-RA was integrated in the CARTO system and used, after correct alignment, as LA-model for PVI. For all index RF-PVI procedures a wide circumferential point-by-point ablation (WACA) was performed on the lateral and septal pulmonary veins. Isolation was confirmed using a 20-pole circular mapping catheter. Ablation was performed using a standardized workflow consisting of a pre-specified procedure sequence including 3D modeling, followed by radiofrequency encircling of the pulmonary veins (25 W posterior wall, 35 W anterior wall) with a THERMOCOOL SMARTTOUCH® Catheter guided by CARTO VISITAG™ Module (2.5 mm/5 s stability, 50% > 7 g) and ablation index (targets: 550 anterior wall, 400 posterior wall).19