Electrophysiology and ablation strategy
Before CA, AAD other than amiodarone were discontinued for at least 5 half-lives. The patients were given anticoagulant medication for over 3 weeks before the procedure. Before LA was ablated, transesophageal echocardiography was performed to confirm that there was no thrombus in the LA. Activated clotting time and sedation protocol were as described previously.12 Intracardiac echo was used to perform septal puncture. If AT persisted, we observed voltage characterization and activation wavefronts of the atrium. If a patient was in sinus rhythm, AT or AF was induced by atrial burst pacing with a stimulation cycle length of up to 180 ms or the local refractory period. Intravenous isoproterenol administration was done as necessary. If AT was not sustained, we looked for the existence of gaps after the Maze procedure. When performing CA, we use an ablation catheter with RF energy (NAVISTAR; Biosense Webster, Diamond Bar, California, USA, THERMOCOOL SMARTTOUCH SF; Biosense Webster or TactiCath SE; Abbott, St Paul, MN, USA) at 15-50 W for 5-60 seconds. All ablation lines were confirmed to be bi-directional blocks. Finally, the aforementioned stimulation protocol was performed to confirm the non-inducibility of AT or AF as an endpoint.