Catheter ablation procedure
Prior to the catheter ablation procedure, all patients underwent transesophageal echocardiography or cardiac computed tomography imaging within 48 hours to rule out the presence of cardiac thrombosis. The procedures were conducted by seasoned physicians. During radiofrequency ablation, a circular pulmonary vein (PV) mapping catheter—either a Lasso or Pentaray by Biosense-Webster Inc.—was utilized in conjunction with a 3D electroanatomical mapping system (NavX, St. Jude Medical Inc.; CARTO 3, Johnson and Johnson, Inc.). A 3.5 mm-tip open-irrigation deflectable catheter (manufactured by Johnson and Johnson Inc. or Coolflex by St. Jude Medical Inc.; operating at 30–45 W, 47°C) was employed for the ablations. All individuals underwent a comprehensive PV isolation, and those presenting with atrial flutter were subjected to routine creation of bidirectional isthmus block. The operators had the discretion to complement the procedure with additional ablations, if deemed necessary. These could include posterior wall isolation, roof lines, ablation at non-PV trigger sites, targeting of complex fractionated atrial electrograms, or isolation of the superior vena cava17,18. The endpoint of ablation therapy is to achieve both electrical entrance block and exit block. If sinus rhythm is not achieved, electrical cardioversion may be performed. For the cryoablation procedure in select patients with paroxysmal AF, either a 23-mm or 28-mm Arctic Front or Arctic Front Advance cryoablation balloon catheter from Medtronic, Inc., was inserted via a guidewire into the orifice of the PV. The choice of the balloon size was determined based on the dimensions of the PV, which were assessed using procedural imaging with contrast-enhanced radiography and computed tomography. The primary aim of the cryoablation was to achieve electrical isolation of the four main PVs; this was verified by demonstrating entrance and/or exit block. The cryoablation process involved 120 to 240-second applications (temperatures not exceeding -55°C). After a waiting period of 30 minutes, the effectiveness of the isolation was checked by employing pacing maneuvers along with a circular mapping catheter to assess for the presence of entrance and/or exit block19.