Clinical impact of esophageal muscle thickness on peroral endoscopic myotomy patients

Peroral endoscopic myotomy (POEM) is a standard procedure for achalasia, an esophageal motility disorder, characterized by a thickened lower esophageal sphincter muscularis propria (LEMP). Visualization of this anatomical stratification has been made possible by the advent of endoscopic ultrasound (EUS). However, the effect of LEMP thickness on treatment outcomes remains unclear. The objective of this study was to investigate whether LEMP thickness affects treatment response post-POEM.

This was a single-center, prospective cohort study of patients who underwent POEM between 2014 and 2021. Patients who underwent EUS to evaluate the LEMP before POEM were included in the study. We divided the patients into two groups according to muscle thickness measured by EUS (≥ 2.80 mm; group 1, < 2.80 mm; group 2). The pre- and post-procedural clinical parameters were compared between the two groups.

Among 278 patients, 189 were enrolled. There were no significant differences in the pre- and post-Eckardt scores, integrated relaxation pressure, and distensibility index between the two groups divided by muscle thickness. Furthermore, there was no statistically significant difference in symptom recurrence, as measured by an Eckardt score > 3, post-procedural complications, or post-POEM GERD symptoms. However, patients with thicker lower esophageal sphincter muscle showed a greater decrease in Eckardt scores (ΔES ≥ 3) which was statistically significant (P = 0.002).

POEM is an effective and safe treatment method for achalasia, regardless of LES muscle thickness. There was a statistically significant difference in the decrease of Eckardt scores of 3 or greater (ΔES ≥ 3) after POEM in the thicker LEMP group suggesting greater alleviation of symptoms in POEM patients with thicker lower esophageal muscle.