Using impedance planimetry to define the end of a peroral endoscopic myotomy

Peroral endoscopic myotomy (POEM) is a minimally invasive endoscopic option for management of achalasia. Adequate distal myotomy is necessary for relief of symptoms, but when too long may also increase risk of reflux. The objective of this study is to evaluate clinical outcomes after POEM and final length of gastric myotomy using impedance planimetry (EndoFLIP).

A retrospective review of 34 consecutive patients undergoing POEM with EndoFLIP were included. EndoFLIP measurements, including esophagogastric junction distensibility index (DI), minimum diameter (D_min), and cross-sectional area (CSA) were recorded at 30- and 40-mL balloon-fill pre- and post- myotomy. The myotomy was considered complete when DI ≥ 3.4 mm²/mmHg. Postoperative Eckardt score (ES) was determined at initial postoperative visit and most recent follow-up. Linear and logistic regression were used to evaluate the association between gastric myotomy length and post-myotomy EndoFLIP measurements on postoperative ES and GERD. Wilcoxon rank-sum test was used to compare gastric myotomy lengths and EndoFLIP parameters in relation to clinical success and development of GERD, and paired t-test to compare EndoFLIP measurements and ES pre- and post-myotomy.

Final length of gastric myotomy measured 1 cm in 1 (2.9%), 1.5 cm in 11 (32.4%), 2.0 cm in 19 (55.9%), and 2.5 cm in 3 (8.8%) patients. Mean preoperative ES was 6.6 ± 2.2. All patients achieved ES < 3 postoperatively, which was maintained in 88.5% of patients at a median of 7.5 months of follow-up. Gastric myotomy length and post-myotomy EndoFLIP values were not associated with postoperative Eckardt scores or GERD.

Early and late symptom relief was achieved in 100 and 88.5% of patients, respectively, at a gastric myotomy length of 1-2.5 cm. Using EndoFLIP to define a completed myotomy at DI of 3.4 mm²/mmHg yielded variable lengths of gastric myotomy.