Catheter ablation procedure
All antiarrhythmic drugs were discontinued for at least 5 half-lives before the procedures. The ablation procedures were performed under deep sedation with boluses of hydroxyzine, pentazocine, and propofol followed by a continuous infusion of propofol and dexmedetomidine. The patients received respiration control with adaptive servo ventilation (ASV). An esophageal temperature monitoring catheter was inserted via the nose. A duo-decapolar catheter (BeeAT; Japan Lifeline, Tokyo, Japan) was placed in the coronary sinus (CS) though the right internal jugular vein or right subclavian vein. A Brockenbrough puncture using an RF needle (Japan Lifeline) was performed under guidance of the Soundstar 3D Ultrasound Catheter (Biosense Webster). After the Brockenbrough puncture, 2 or 3 long sheaths (SL0; Abbott, Chicago, IL, USA) were inserted into the LA. An initial intravenous bolus of heparin (100IU/kg body weight) was administered followed by a continuous infusion of heparin to maintain the activated clotting time at 300-350 seconds. One or two circular mapping catheters were placed in the superior and inferior pulmonary veins (PVs), and the ipsilateral PVs were circumferentially ablated guided by the CARTO3 mapping system. All PVI was performed with the CF-sensing open-irrigated-tip ablation catheter. The endpoint of the PVI was the achievement of bidirectional conduction block between the LA and PVs. After the achievement of the PVI, isoproterenol (20-300μg/h) and 40mg adenosine triphosphate (ATP) were infused to examine any dormant PV reconnections and non-PV AF triggers. A non-PV trigger ablation was strongly encouraged. Cavo-tricuspid isthmus (CTI) block was created in almost all patients.
Ablation procedures performed between September 2014 and July 2018 were CF-guided, whereas those between August 2018 and August 2019 were AI-guided. In the CF-guided ablation, lesion creation was guided by CF targets of 5-40g. Each radiofrequency application was delivered for 25 seconds with a power of up to 30W. In AI-guided ablation, the procedure was guided by AI target values for each lesion as follows: 450 for the anterior/roof segments and 400 for the posterior/inferior segments of the LA. In both groups, the esophageal temperature was monitored continuously during the ablation procedure to avoid any thermal injury, and the radiofrequency delivery was terminated immediately when the esophageal temperature reached > 40℃.