AI guide ablation on the esophagus region
AI was developed as a novel marker of lesion size that incorporates
contact force and RF application power and time. By an in vitro
experimental study, Kawaji, et al. demonstrated that AI was strongly
correlated with lesion depth,19 and the lesion depths
by the target AI values of 300, 400, and 500 were 3.2 mm (interquartile
range, 2.9-3.6), 4.9 mm (4.6-5.3), and 5.8 mm (5.4-6.3), respectively.
Importantly there were no differences in lesion depths among RF powers
(25W, 30W, 35W) used. In the present study, we used a relatively low AI
value 260 on the esophagus region, and PV isolation could be
accomplished without residual conduction gap at the LA posterior wall on
the esophagus in most of the patients (88%). It may be noted that the
inter-lesion distance was <4 mm in circumferential PV
isolation including the esophagus area, and this relatively close lesion
formation might have enhanced the effect of AI-guide ablation with a
relatively low AI value.
Atrioesophageal fistula20,21 and injury to
peri-esophageal vagal plexus22 are known complications
of the circumferential PV isolation that are likely to be related to the
excessive exposure to RF on the LAPW and esophagus. In the recent
Power-AF study, Wielandts et al. reported that severe esophageal region
was seen by CLOSE-guide AF ablation using AI value >400
posteriorly,23 and recommended reducing AI up to 300
as preventive measure for posterior wall RF application in proximity of
the esophagus. We did not perform an endoscopic examination and
therefore asymptomatic esophageal injury could be not ruled out.
Considering the fact that there was one patients with gastroparesis, a
careful RF application should be required even with the use of a low AI
value 260.