S1350 Relation of Increased Pyloric Diameter and Distensibility Measured by EndoFLIP to Improved Gastric Emptying After G-POEM for Refractory Gastroparesis

Abstract

INTRODUCTION: Gastric per-oral endoscopic myotomy (G-POEM) to treat gastroparesis works by decreasing pyloric outlet obstruction. G-POEM is effective in some, but not all patients, suggesting multiple causes of gastric emptying delay. Impedance planimetry with EndoFLIP (Functional Lumen Imaging Probe) measures pyloric function before and after G-POEM. The relation of improvements in pyloric functional parameters to acceleration of gastric emptying after G-POEM is unproven. We compared EndoFLIP measurements of pyloric diameter and distensibility after endoscopic myotomy to normalization of gastric emptying rates in an initial series of patients with refractory gastroparesis who underwent G-POEM. METHODS: 13 patients with refractory gastroparesis underwent gastric emptying scintigraphy before and after G-POEM. Pyloric EndoFLIP was conducted with balloon inflation to 30-50mL. Pre- and post-myotomy mean pyloric diameter and distensibility were compared in those without and with normalization of gastric emptying (< 10% 4 hr scintigraphic retention) performed approximately 3 months after G-POEM. RESULTS: Gastric emptying was normal after G-POEM in 5 patients (4 hr retention 4 ± 4%) and abnormal in 8 patients (4 hr retention 27 ± 23%) (P = 0.05). In the whole group, mean pyloric diameter increased from 13.5 ± 2.1 to 16.2 ± 2.7mm on 40 mL inflation (P < 0.0001) and distensibility increased from 5.1 ± 1.8 to 8.2 ± 4.6mm2/mmHg on 50mL inflation (P = 0.01). Figure 1 shows similar antropyloroduodenal diameters in relation to gastric emptying normalization before and after G-POEM. Increases in pyloric diameter were not different in those with normal vs. abnormal gastric emptying (3.3 ± 1.1 vs. 1.4 ± 1.7mm) (P = 0.25). Figure 2 shows that pre- and post-myotomy pyloric distensibility and increases in distensibility were similar in those with normal vs. abnormal gastric emptying after G-POEM. CONCLUSION: Mean pyloric diameter and distensibility measured by EndoFLIP increased after G-POEM for refractory gastroparesis. These increases were similar in patients who normalized their gastric emptying after myotomy compared to those who did not. This raises the possibility of two gastroparesis subtypes—patients primarily with pyloric dysfunction who respond to G-POEM and those who do not respond who likely have primary antral or fundic impairments. Confirmation of these initial findings will require larger cohorts.Figure 1.: Pre- and post-myotomy antropyloroduodenal diameters measured by EndoFLIP were similar in patients who had normal vs. abnormal gastric emptying after G-POEM.Figure 2.: Distensibility pre- and post-myotomy and net increases in distensibility after myotomy were similar in patients who had normal vs. abnormal gastric emptying after G-POEM.