AF ablation procedure
Linear point-by-point ablation RF application on the ipsilateral PV antrum was performed in the 3D image with the use of a Thermocool SmartTouch Surround Flow catheter (Biosense Webster) in all patients. RF power was delivered at 50W at the anterior wall, 40W at the posterior wall, and 25W on the esophagus region, which was identified by the 3D esophagus image (Figure 2 ), under the AI guide. A target AI was set at ≥400 at the anterior, ≥360 at the posterior wall and ≥260 on the esophagus in each ablation point based on our previous prospectively study.10 The VisiTag setting were as follows: For location stability, minimum time was 3 seconds and maximum range 2.5mm; force over time was 30% with a minimum force of 3g. The lesion tag size was 2 mm in radius. The inter-lesion distance used for circumferential PVI was <4mm.
After the circumferential RF application for the PV antrum, a multielectrode catheter (Pentaray Nav Catheter; Biosense Webster) was inserted to the left and right PVs to confirm the disappearance of the PV and PV antrum potentials. The PV-to-LA conduction block was confirmed by pacing from the 10 pairs of the Pentaray catheter placed at the ostium of the PV at an 10-mA output with 1-ms pulse width.
Isoproterenol (10-20 µg) was given as a bolus to induce non-PV AF triggers or non-PV premature contractions in all patients and when they were induced, ablation was attempted. The additive ablation procedures including the LA posterior wall isolation and superior vena cava isolation were done at the discretion of the operators.