Ablation procedure
Deep sedation was performed with a continuous infusion of propofol and fentanyl. A 9-French (Fr) long sheath, a 7-Fr long sheath, and an 8.5-Fr long sheath (SL-1) were introduced through the right femoral vein. Intracardiac echocardiography (ICE; ViewFlex™, Abbott, Inc., USA) was used to identify the absence of thrombi in the left atrium (LA) or LA appendage before transseptal puncture and to guide the appropriate transseptal puncture for CBA in all patients. After a single transseptal puncture, the SL-1 sheath was exchanged with a 15-Fr steerable sheath (FlexCath™, Medtronic, USA). The cryoballoon (CB) catheter (CB2; Arctic Front AdvanceTM, Medtronic), assembled with an intraluminal mapping catheter (20 mm, Achieve™, Medtronic), was gently advanced through the steerable sheath until it reached the distal CB shaft marker to the entrance of the steerable sheath. The CB catheter was advanced over the intraluminal mapping catheter inserted into each PV and inflated. After advancing the inflated CB to each PV antrum, Doppler ICE imaging was used to identify the complete occlusion of each PV. With best-fit occlusion, the mapping catheter was used to obtain PV potential recordings for real-time monitoring of PVI. The dosing regimen was different depending on the time to isolation (TTI, time from freeze initiation until loss of PV potentials). An initial freeze was delivered for 3 min if the TTI was ≤30 s. Otherwise, the initial freeze was delivered for 4 min. The freeze stopped and reposition of the CB catheter was performed if the TTI was not achieved or the temperature did not reach –40℃ for 60-s freezing. After PVI, a bonus freeze was applied for 2 min at the more antral side of each PV to create a wide antral circumferential ablation. To avoid phrenic nerve palsy, diaphragmatic stimulation was achieved by pacing the ipsilateral phrenic nerve with a 900 ms cycle and a 20 mA output during right-sided CBA. A fisherman’s knot suture closure without protamine injection was performed to obtain femoral venous hemostasis following sheath removal. After 6 h of immobilization, puncture sites were inspected. NOAC was taken at the scheduled time on the day of the procedure after confirming complete hemostasis or the absence of bleeding complications.