Atrial fibrillation ablation technique:
The ablations were performed by three different operators (RR, LAS, UC). As previously reported9, the procedure was performed under uninterrupted warfarin therapy (aiming for an INR of 2 on the day of the procedure) or after skipping a single dose of new oral anticoagulants (NOAC). The ablation procedure was conducted under general anesthesia. One decapolar (Livewire decapolar, St. Jude Medical, Minneapolis, USA) and 1 quadripolar catheter (Biosense Webster, Inc) were positioned in the coronary sinus and the His bundle position through the right femoral vein. An intracardiac echocardiogram (ICE) probe (ACUSON Acunav,  Siemens Medical Solutions USA, Inc) was positioned in the right atrium through a 9F or 11F sheath introduced in the left femoral vein. One 8.5F long sheath (SL1, St. Jude Medical, Minneapolis, USA) was introduced into the left atrium with a single trans-septal puncture under ICE guidance. Intravenous bolus of heparin was injected intravenously just prior to the trans-septal puncture and repeated as needed to maintain an activated clotting time (ACT) of >350 seconds throughout the procedure. As routine in our department, the PVs were visualized by selective angiography using a N.I.H angiography catheter (N.I.H 6F, Cordis, Miami Lakes, FL, USA).
m-FAM workflow with ablation catheter (group 1) :
The ablation catheter was introduced through the original SL1 sheath into the left atrium. In case of difficulties in manipulation the ablation catheter in the left atrium, the SL-1 sheath was replaced with a steerable sheath (Agilis 8.5F, St. Jude Medical, Minneapolis, USA). The ablation catheter was first introduced deep into the PVs. Then the catheter was withdrawn and specific landmarks at the pulmonary vein ostium were tagged (magnet points) on the system for reconstruction. These magnet points are represented by the drop-point from the left superior to the left inferior and from the left inferior back to the left superior (i.e carina), the drop-point from the left inferior to the left atrium, the drop-point from the left superior to the left atrial appendage, the anterior and posterior borders of the left inferior pulmonary vein were tagged. On the septal side, we tagged the anterior and posterior drop point from the right superior pulmonary vein to the left atrium, the drop-point from the right superior to the right inferior pulmonary vein (i.e carina), the drop-point from the from the right inferior pulmonary vein to the left atrium and the anterior and posterior borders of the right inferior pulmonary vein at the ostium. Additional magnet points were tagged at the anterior and posterior left atrium and at the mid roof. These magnet points are needed to better define the shape and volume of the left atrial body. At this moment the m-FAM algorithm was initiated to create a three-dimensional reconstruction of the left atrium.
Upon acquisition of the m-FAM reconstruction, the accuracy of the m-FAM reconstruction and location of the specific landmarks at the pulmonary veins ostium were checked with fluoroscopy and ICE visualization (Figures 1 and 2).