Intra-procedural setting
Electrophysiological study and ablation procedure was performed under
conscious sedation with fentanyl and midazolam. A deflectable decapolar
catheter was positioned in the coronary sinus (CS). An 8.5-French-long
sheath (SL1; St. Jude Medical, Minnetonka, USA) was introduced into the
LA using a modified Brockenbrough technique. To prevent thrombus
formation, the transseptal sheath was continuously flushed with
heparinized saline (20 mL/h) and i.v. heparin was administered to
maintain an activated clotting time of 300–350 seconds. The LA was
reconstructed under the guidance of a three-dimensional electroanatomic
mapping system (CARTO, Biosense-Webster, Inc.) using a high-density
mapping catheter (PENTARAY® Catheter Biosense-Webster Inc.). The
catheter ablation was performed with a 3.5-mm cool saline-irrigated
ablation catheter (Thermo-Cool SMARTTOUCH SF® Catheter. Biosense-Webster
Inc, Diamond Bar, CA, USA). Point-by-point application was performed
using power-control mode, with a temperature limited under 43°C and a
saline irrigation rate of 8-30 mL/min. RF energy was delivered with a
power output of 25 W in the CS and 35-50 W elsewhere. Radiofrequency
applications were depicted using automated tagging technology (Carto
VisiTagTM, Biosense Webster Inc.), with a filter threshold of catheter
motion <2.5 mm within 4 seconds and contact force ≥8g for 70%
of the time. Targets for ablation index (AI) were: (1) 500-550 for
anterior wall; (2) 350-400 for posterior wall; (3) 450-500 for the LA
roof and CTI; (4) 550-600 for MI.