The effect of per-oral endoscopic myotomy by achalasia subtype as measured by impedance planimetry

BackgroundAchalasia is an esophageal motility disorder with three subtypes based on manometry that can treated with per-oral endoscopic myotomy (POEM). With the advent of impedance planimetry (EndoFLIP (R)), we hypothesized the three achalasia subtypes would have different pre-POEM EndoFLIP (R) diameter and distensibility index (DI) measurements but would be similar after POEM.MethodsA single-institution, retrospective review of consecutive POEM cases by a single surgeon-endoscopist team from 04/07/2017 to 08/28/2023. Patients with a diagnosis of achalasia were stratified into type 1, 2, or 3 based on pre-POEM manometry. Patient characteristics, Eckardt scores, and pre-and-post-POEM diameter and DI were compared by subtype with descriptive, univariate, and multivariable linear regression statistics.ResultsSixty-four patients met inclusion criteria, of whom 9(14.1%) had Type 1, 36(56.3%) had Type 2, and 19(29.7%) had Type 3. There were no differences between Types with respect to median pre-POEM Eckardt scores (9[IQR:7-9) vs. 8[IQR:6-9] vs. 7[IQR:5-8], p = 0.148), median post-POEM Eckardt scores (0[IQR:0-1] vs. 0[IQR:0-0] vs. 0[IQR0-0.5], p = 0.112). EndoFLIP (R) data revealed variation in median pre-POEM diameter and DI between Subtypes (6.9[IQR:6-8.5] vs. 5.5[IQR:5-6.8] vs. 5[IQR:5-6.1], p = 0.025 and 1.8[IQR:1.3-3.2] vs. 0.9[IQR:0.6-1.6] vs. 0.6[IQR:0.5-0.8], p = 0.003, respectively), but not in the change in diameter or DI post-POEM (5.1[IQR:4.3-5.9] vs. 5.1[IQR:4.1-7.1] vs. 5.9[IQR:5-6.4], p = 0.217 and 3.9[IQR:2.5-4.7] vs. 3.4[IQR:2.4-4.7] vs. 2.7[IQR:2.3-3.7], p = 0.461, respectively). However, after adjusting for potentially confounding factors, pre- or post-POEM diameter and DI did not demonstrate statistically significant differences among subtypes.ConclusionsAchalasia subtypes did not demonstrate different pre-POEM diameters or DI as measured by EndoFLIP (R) nor are there differences after POEM completion. While achalasia subtypes may have slightly different pathophysiology based on manometry findings, similar pre- and post-POEM impedance planimetry findings, along with similar Eckardt scores, support the use of POEM in the treatment of any achalasia subtype.