Peroral Endoscopic Myotomy-Induced Reduction of Crural Diaphragm Contractility Might Contribute to Development of Postprocedural Reflux Esophagitis

INTRODUCTION: Reflux esophagitis (RE) frequently occurs after peroral endoscopic myotomy (POEM). However, its underlying mechanism has not been completely understood. POEM may cause pathological gastroesophageal reflux by impairing the crural diaphragm (CD), a key component of the antireflux barrier. The aim of this study was to investigate the impact of POEM on CD function and its association with post-POEM RE. METHODS: We retrospectively analyzed patients who underwent POEM and completed routine 3-month follow-up between January 2018 and February 2025. In the follow-up, esophagogastroduodenoscopy and high-resolution manometry assessed post-POEM RE and CD function (i.e. inspiratory augmentation of esophagogastric junction [EGJ] pressure), respectively, after a 1-month cessation of acid-suppressive therapy. A subset of patients also underwent the same follow-up protocol 1 year post-POEM. We examined changes in CD function after POEM and identified factors associated with post-POEM RE using logistic regression. RESULTS: Ultimately, 200 patients were analyzed. Inspiratory augmentation of EGJ pressure significantly decreased 3 months post-POEM compared with preoperatively ( P = 0.011) and partially recovered from 3 months to 1 year post-POEM. RE (grade B or higher) was observed in 102 patients (51%) 3 months post-POEM. This RE group showed significantly weaker inspiratory augmentation of EGJ pressure compared with the non-RE group (none or grade A) ( P < 0.001). Multivariable analysis demonstrated that weak CD contraction was associated with post-POEM RE, along with older age and several modifiable factors such as alcohol consumption, smoking, and gastric myotomy length. DISCUSSION: POEM can impair CD contraction, and weak CD contraction was associated with post-POEM RE.