Catheter ablation
All patients entered the EP laboratory after fasting for at least 8 hours and after a transesophageal echocardiography performed the day prior to the procedure had excluded the presence of left atrial thrombi. Right and left femoral veins were cannulated. A steerable catheter (Inquiry, Abbott, St. Paul, MN, USA) was positioned inside the coronary sinus. The ICE catheter (ViewFlex Xtra, Abbott, St. Paul, MN, USA) was positioned in the right atrium. The transeptal puncture was performed under radioscopic and ICE guidance. A multipolar mapping catheter (Advisor HD Grid, Abbott, St. Paul, MN, USA) was used for mapping. A 3.5 mm irrigated-tip radiofrequency ablation catheter (TactiCath, Abbott, St. Paul, MN, USA) was used to perform ablation. The NavX 3D electroanatomic mapping (EAM) system (Abbott, St. Paul, MN, USA) was used in every procedure to guide catheter ablation and reduce fluoroscopy use. PV isolation with wide antral circumferential approach was performed for every de novo ablation procedure. For redo procedures, conduction gaps were identified and the PV re-isolated. A vein was defined as isolated when PV potentials disappeared/were dissociated from the left atrium and exit block from the vein was demonstrated. Heparin was given to maintain an activated clotting time of 250–300 s throughout the procedure.