Changes in Distensibility Index During an Incremental POEM Myotomy

Background: A longer myotomy for the treatment of achalasia is associated with worse gastroesophageal reflux disease despite palliating dysphagia. Recently, clinical outcomes have been correlated to the distensibility of the distal esophagus, which is measured intra-operatively using an endoscopic functional luminal image probe (EndoFLIP). We aimed to determine the minimum per oral endoscopic myotomy (POEM) length to allow for adequate distensibility index (DI). Methods: A 6-cm myotomy conducted in 2-cm increments during POEM was performed for patients with achalasia I and II from 2017 to 2019. The EndoFLIP was used to measure the DI intra-operatively: (1) prior to intervention, (2) following creation of the submucosal tunnel, (3) following transection of the high-pressure zone (HPZ), (4) following the distal extension, and (5) following the proximal esophageal extension. Results: A total of 16 patients underwent POEM. Ages ranged from 21 to 78 years, 10 were male, and 13 had type II achalasia. The median DI was 2.7 (1.4–3.6) mm²/mmHg prior to intervention; 2.4 (1.4–3.3) mm²/mmHg following the submucosal tunnel; 3.2 (1.6–4.4) mm²/mmHg following transection of the HPZ; 3.8 (2.6–4.5) mm²/mmHg following the gastric extension; and 4.5 (3.3–7.1) mm²/mmHg following the proximal extension. Our target range DI was achieved for 50% of patients after transection of the HPZ. Conclusions: Distensibility changed with each myotomy increment and fell within the target range for most patients following a 2–4-cm myotomy. This suggests that a shorter myotomy may be appropriate for select patients, and the use of the EndoFLIP intra-operatively may allow for a tailored myotomy length.