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

Background Achalasia 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®), we hypothesized the three achalasia subtypes would have different pre-POEM EndoFLIP® diameter and distensibility index (DI) measurements but would be similar after POEM. Methods A 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. Results Sixty-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® 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. Conclusions Achalasia subtypes did not demonstrate different pre-POEM diameters or DI as measured by EndoFLIP® 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. Graphical abstract