Muscle layer thickness affects the peroral endoscopic myotomy procedure complexity.

Esophageal motility disorders can cause severe dysphagia, regurgitation, and/or noncardiac chest pain due to a lack of coordinated esophageal motility function. However, the clinical significance of esophageal muscle layer thickness remains unclear. The aims of this study are to elucidate the clinical significance of esophageal muscle layer thickness in patients with esophageal motility disorders who undergo peroral endoscopic myotomy (POEM), and to identify predictors of a longer POEM procedure time. Seventy-four consecutive patients with esophageal motility disorders who underwent POEM procedures at Kobe University Hospital from April 2015 to December 2016 were prospectively recruited into this study. First, we investigated the associations between the thickness of the esophageal muscular layer and clinical parameters. There were no significant differences, except in the POEM procedure time, between the patients with esophageal muscle layer thickness values of ≥1.5 mm (group A) and <1.5 mm (group B). However, the relative frequency of a longer POEM procedure time (≥78 min) was significantly higher in group A than in group B (66.7% vs. 19.5, P < 0.0001). Next, independent clinical factors that were related to longer POEM procedures were investigated. Multivariate logistic regression analysis with stepwise selection demonstrated that a thick esophageal muscle layer and the length of myotomy were an independent predictor of a longer POEM procedure (odds ratio: 13.9 and 12.0, respectively). Our results indicate that preoperative endoscopic ultrasonography evaluations can help to predict the technical complexity of POEM procedures.