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.