Ablation procedure
All patients provided their written informed consent before the
ablation procedures. All patients received effective anticoagulation
therapy with a direct oral anticoagulant for >1 month.
Catheterization of the LA was performed using a 1-puncture 2-sheath
technique. Unfractionated heparin was administered intravenously to
maintain an activated clotting time of 300–350 s after the transseptal
puncture. Thereafter, a 3.5-mm irrigated ablation catheter with contact
force monitoring (ThermoCool Biosense Webster; Biosense Webster, Inc.,
Diamond Bar, CA, USA) and Pentaray Catheter (Biosense Webster, Inc.)
were introduced through the sheaths. Bilateral circumferential PV
isolation was performed using a 3D mapping system (CARTO3; Biosense
Webster, Inc.). The radiofrequency current was delivered point-by-point
for 30–35 s with a power of up to 35 W, a target temperature of
<43°C, and an irrigation rate of 30 ml/min. The power of the
radiofrequency current was limited to 25 W on the posterior wall close
to the esophagus. The endpoint of PV isolation was bidirectional
conduction block of the PVs identified by a multipolar catheter. If AF
continued after this procedure, internal electrical cardioversion was
performed. Additional ablation, such as that of the LA linear
lesion (LA roof line and mitral isthmus line) and regions with complex
fractionated electrograms, was performed if the AF could not be
electrically cardioverted after PV isolation. After restoration of sinus
rhythm, a cavotricuspid isthmus line was created with the endpoint of
bidirectional conduction block in all patients. If there were non-PV
foci under isoproterenol infusion (5–10 μg/min), we ablated them.