Electrophysiological study and ablation procedure

Patients received oral anticoagulation with vitamin K antagonists (VKA) or non-VKA oral anticoagulants for at least four weeks prior to the procedure depending on their CHA₂DS₂-VASc scores. Patients underwent transoesophageal echocardiography within 48h before the procedure to rule-out atrial thrombus. Immediately before transseptal puncture, intravenous heparin (100IU/kg) was administered, and was repeated during the procedure depending on regular measurements of activated clotting times (ACT), with a target ACT of 300-400sec. The ablation procedure was guided by three-dimensional electroanatomic mapping (CARTO 3, Biosense Webster). Catheter ablation of the pulmonary veins (PVs) was performed using a 3.5 mm irrigated tip catheter (ThermoCool SmartTouch, Biosense Webster) with a standard power setting of 30W for the anterior portions of the atrium and 25W for the remaining left atrium. A 10-polar lasso catheter (CARTO Lasso, Biosense Webster) was used for fast anatomical mapping and to control entrance and exit block within all four PVs. Wide antral circumferential contact force guided PV isolation (PVI) was performed with the endpoint of abolition or dissociation of electric activity of all PVs. Successful PVI was checked after a 20-minute waiting period including sinus rhythm control and entrance-block pacing. None of the patients underwent more extensive ablations (such as linear ablation, ablation of complex fractionated electrograms, rotor ablation). In case of documented typical right atrial flutter, additional cavotricuspid isthmus ablation was performed during CS pacing until bidirectional block was achieved.

Anticoagulation was restarted the day of the procedure for at least three months after the ablation procedure and was continued thereafter at the physician’s discretion.