Catheter ablation procedures
The ablation procedure was performed using a minimal sedation strategy while keeping the patient conscious. An 80–100 IU/kg bolus of heparin was administered immediately after sheath insertion, and the target range for an activated clotting time of 300–350 s was maintained using additional heparin infusions.
This study included four catheter ablation techniques (radiofrequency, cryoballoon, hot balloon, and laser balloon ablation). Radiofrequency and cryoballoon ablation were performed in most cases. The radiofrequency ablation method was described previously.7 Two 8-Fr sheaths and an 8.5-Fr steerable sheath were introduced into the LA through a trans-septal puncture using intracardiac echocardiography (ICE). The electrical pulmonary vein (PV) isolation was performed using a circular mapping catheter placed on the ostium of the PV. The ablation procedures were performed using a 3D mapping system. We have used a 3.5-mm-tip open-irrigated ablation catheter and contact force-sensing ablation catheter since 2009 and 2013, respectively. The radiofrequency energy output was adjusted to 20–35 W at a flow rate of 8–30 mL/min, with a maximum temperature of 42°C. The contact force was targeted as 10–20 g, and the maximum contact force threshold was set to 50 g. In most patients with paroxysmal and early persistent AF, we only performed PV isolation and cavotricuspid isthmus ablation. However, additional linear and substrate ablations were applied in patients with atrial flutter or long-term persistent AF. If sinus rhythm was not achieved by the end of the ablation, external cardioversion was performed.
For the cryoballoon ablation procedure, a 12-Fr steerable sheath was inserted into the LA. A second-generation 28-mm cryoballoon system (Arctic Front Advance, Medtronic) was advanced into the ostium of each PV using an inner circular mapping catheter. After confirming the PV occlusion with the cryoballoon, a 120–180-s cycle freeze ablation was repeated until electrical isolation of the PV was achieved. Other hot balloon and laser balloon ablations were performed according to the standard approach as per the recommendation of the manufacturer and expert consensus reports.3