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.