RF ablation
All ablation procedures were performed under general anesthesia. Femoral
site access was
obtained, and intravenous heparin administered to maintain activated
clotting times >350 s.
After performing a double transseptal puncture,
PentaRay mapping catheter
(Biosense-Webster, Diamond Bar, California) was positioned in the left
atrium. An electroanatomic map of the left atrium was obtained using the
CARTO system (Biosense-Webster) and superimposed on pre-acquired CT
scan. A 4-mm open-tip irrigated RF catheter (Thermocool or Thermocool
SmartTouch, Biosense-Webster) was then positioned in the left atrium: PV
isolation (PVI) was performed using real-time automated display of RF
application points (Visitag, Biosense-Webster) with predefined catheter
stability settings. Starting energy delivery parameters were 25 to 40 W
on the posterior wall and 35 to 45 W at other sites. Target contact
force was between 5 and 20 g for cases performed after 2014 with the
Thermocool Smart Touch catheter. Esophageal temperature was monitored,
and the RF delivery paused if the esophageal temperature increased by
0.5°C. Electric isolation of PVs was confirmed by entrance block to
individual PVs, assessed by PentaRay catheter positioned at the PV
antrum.