Assessment of Different Modified POEM for Achalasia

The aims of this study are 1) to compare the efficacy and safety of conventional myotomy (long myotomy) and modified myotomy (short myotomy) in the treatment of type I/II achalasia patients diagnosed according to Chicago Classification; 2) to compare the efficacy and safety of conventional myotomy (circular myotomy) and modified myotomy (full-thickness myotomy) in the treatment of type I/II achalasia patients; 3) to compare the efficacy and safety of conventional myotomy (non-tailored myotomy) and modified myotomy (tailored myotomy) in the treatment of type III achalasia patients.

Peroral endoscopic myotomy (POEM) is a novel clinical technique used to treat achalasia. The conventional POEM myotomy length averages 8 to 10 cm (4-6 cm in the esophagus, 2-4cm in the LES, 2cm in the cardia \& 6-8 cm above and 2 cm below the gastroesophageal junction \[GEJ\]) for typical achalasia (Chicago classification I, II), but there is no guideline or expert consensus with regard to minimal myotomy length recommended in POEM.

Based on the facts that achalasia is a primary motor disorder of LES dysfunction, patients with type I/II achalasia may achieve a satisfactory outcome with shorter myotomy in procedure of modified POEM, which only focused on the forced relaxation of the LES. Recently, some retrospective studies have suggested that shorter myotomy is comparable with longer myotomy for treating achalasia with regard to clinical efficacy and has the advantage of shorter procedure time, which needs to be further confirmed by more prospective studies.

In terms with the International Peroral Endoscopic Myotomy Survey, a longer myotomy is recommended for patients with type III achalasia. The length of myotomy in type III achalasia can be gauged by high-resolution manometry (HRM). Recent research showed that postoperative Eckardt score was significantly improved in the tailored group (myotomy length informed by HRM) versus non-tailored for type III achalasia, but this study was limited by its retrospective nature.

There is still no conclusion on the thickness of muscle bundle dissection recommended during POEM. Selective circular muscle myotomy is designed to avoid gastroesophageal reflux (GER) postoperatively and decrease morbidity during POEM. But one meta-analysis showed that Heller's surgery could keep patients in long-time remission, mainly because of its full-thickness muscle bundle dissection to make sure of persist relaxation of LES. A retrospective study comparing the outcomes of full-thickness and circular muscle myotomy showed no differences in efficacy, GER or adverse events, although the procedural time was shorter in the full thickness myotomy group.

Further randomized controlled trials are warranted to assess the efficacy and safety of different modified myotomy approaches in POEM for patients with achalasia.

Eligibility Criteria:
Inclusion Criteria:

* Subjects diagnosed as achalasia type I, II, or III on the basis of the results of established methods (barium swallow, manometry, esophagogastroduodenoscopy)
* Candidate for a POEM
* No contra-indication to general anesthesia
* Their age is ≥14years and ≤70 years
* Able to give written consent

Exclusion Criteria:

* Previous myotomy for achalasia: any of previous Heller myotomy, endoscopic myotomy
* Previous mediastinal surgery
* Any anatomical esophageal anomaly that in the opinion of the investigator may render the intervention more difficult, such as sigmoid esophagus on the pre-operative barium swallow, esophageal diverticula or hiatal hernia.
* Any medical condition, which in the judgment of the Investigator and/or designee makes the subject a poor candidate for the investigational procedure
* Pregnant or lactating female
* Subjects with coagulopathy