Assessment of Clinical Outcomes after Peroral Endoscopic Myotomy via Esophageal Distensibility Measurements with the Endoluminal Functional Lumen Imaging Probe.

Background/Aims: Endoluminal functional lumen imaging probe (EndoFLIP) is a modality that enables clinicians to measure volume-controlled distension of the esophagus. This study aimed to assess the utility of EndoFLIP in patients who had achalasia treated with peroral endoscopic myotomy (POEM). We hypothesized that improvement in the distensibility index (DI) is correlated with the postoperative clinical outcome of POEM.

Methods: Patients who underwent POEM for achalasia at Cha Bundang Medical Center were included. Physiological measurements of the lower esophageal sphincter (LES) pressure before and after POEM were assessed using EndoFLIP. Patients' symptoms were recorded using the Eckardt score.

Results: A total of 52 patients with achalasia were included in this study. Patients with a post-POEM DI below 7 (30 or 40 mL) had a significantly higher rate of incomplete response after POEM (p=0.001). Changes in LES pressure or integrated relaxation pressure after POEM were also significantly associated with an incomplete response (p=0.026 and p=0.016, respectively). Multivariate analysis showed that post-POEM DI ＜7 was the most important predictor of an incomplete response after POEM (p=0.004).

Conclusions: Lower post-POEM DI values were associated with an incomplete post-POEM response. Therefore, post-POEM DI at the esophagogastric junction using EndoFLIP is a useful index for predicting the clinical outcome of POEM in patients with achalasia.