PVI
PVI was performed by two electrophysiologists (MH and MK) with more than 500 case experiences of AF ablation before the study. RF energy was applied in a point-by-point manner using an open-irrigated catheter equipped with a CF sensor (Thermocool Smarttouch® SF, STSF, Biosense Webster, Diamond Bar, CA, USA).
Before AI technology was introduced to our facility, AI-blinded retrospective analysis was performed by the medical device manufacturer (Biosense Webster) to estimate optimal AI for a first-pass isolation in standard PVI (n=5 in each operator).
Target CF was10-30g (irrigation flow rate: 8 ml/min for ≤30W, 15 ml/min for >30W, power control mode). Contiguous RF region was ensured by targeting an inter-lesion distance ≤6 mm.4The ablation lesion sets encircling the PV antra were created >5 mm outside the PV ostia, where the local electrograms did not show near-field PV signals. For the anterior segment in the left-PV (the left lateral ridge), RF delivery was applied only to the inside (<5 mm) of the left-PV ostium. The RF ablation on the inter-PV carina was not performed as a part of initial lesion set, unless it was needed to achieve PVI. No additional linear ablation in the LA was performed, and only cavotricuspid isthmus ablation was permitted for documented typical atrial flutter. RF energy was delivered at 30-40W in power-controlled mode but was decreased to 20-30W at the posterior/bottom segments if esophageal temperature exceeded 39℃ (irrigation flow rate: 8 ml/min for ≤30W, 15 ml/min for >30W). The LASSO NAV catheter was placed inside the ablation line of PVI. The success of first-pass isolation was defined as the electrical isolation of ipsilateral PV which occurred either before or at completion of the RF lesion sets without the ablation of the inter-PV carina. After the circular RF application, electro-anatomical mapping was performed using the PENTARAY catheter. If residual PV potentials and/or conduction gaps within the isolated area were observed, additional RF ablation was performed to eradicate them. Conduction block from the PV to the LA was confirmed by high-output pacing (20 V output, 1 msec pulse) from the isolated PV area at the both sides. After a 20-minute waiting period, boluses of isoproterenol (2-4 μg) and adenosine triphosphate (20 mg) was administered. If spontaneous PV reconnection and/or drug-evoked dormant conduction were observed, an additional RF application was done to eliminate it.