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