COMMENTARY

Peroral Endoscopic Myotomy (POEM): The Future Is Now

David A. Johnson, MD

Disclosures

September 23, 2016

Innovative Technique Offers Hope for Those With Achalasia

Peroral endoscopic myotomy (POEM) is an exciting innovation for the treatment of achalasia. According to published studies in approximately 1000 patients, POEM has a clinical success rate ranging from 82% to 100%, with a self-limited adverse event occurrence of < 10% and no mortality.[1] Although these successful outcomes largely come from expert centers, they are nonetheless extremely and consistently impressive.

In a recent report, Dr Hirano Inoue—recognized as the "master" of this procedure—reflected on the technical precision that POEM requires and the lessons learned from the first 1000 cases treated using this technique.[2] Inoue and colleagues note that there are key anatomic landmarks for this submucosal dissection that are important to recognize, including the aortic arch, left main bronchus, and left atrium. As all of these abut and impinge on the esophagus, using wrong dissection planes here could be catastrophic. This is also recognizably a submucosal dissection of the esophagus, which has no serosa on the other side of the muscular layer. The mediastinum awaits any unintended and misdirected advance.This procedure is not for the timid or faint of heart.

In their recent report, Dr Hirano's group details the trainee pathway and time frames for this advanced technique.[2] Analyses of operator learning curves show a plateau at 20 procedures, efficiency after 40 procedures, and mastery after 60 procedures.

Contraindications to performing POEM are severe pulmonary disease, cirrhosis with portal hypertension, severe coagulopathy, and severe esophageal submucosa fibrosis (eg, from irradiation). Conversely, POEM has been shown to be effective in end-stage achalasia (severe sigmoid achalasia or megaesophagus) and does not preclude surgical esophagectomy if unsuccessful. Excellent clinical efficacy is observed, but it has been reported that dissection might be more challenging with prior failed Heller myotomy.

The targeted length of the myotomy should be ≥ 6 cm (beginning 2 cm in cardia), and is 8-10 cm on average. Longer myotomies have been performed with successful outcomes in patients with well-defined spastic esophageal disorders, including spastic achalasia (Chicago classification type III), jackhammer esophagus, and diffuse esophageal spasm. This is the treatment of choice for patients with type III achalasia who have a high rate of problematic chest pain after both standard Heller myotomy and pneumatic dilation, likely owing to the relatively short length of muscular disruption limited by these two approaches to the distal esophagus. Although there are no specific randomized controlled trials comparing these approaches for type III, the longer myotomy achievable with POEM seems to be much more effective in this subclass. At present, this is my primary direction for these patients.

POEM's safety profile has been notably excellent, despite the dissection field adjacent to several vital mediastinal structures. With over 5000 cases performed to date, remarkably there have been no reported mortalities or conversion to open surgery. The more notable, yet relatively uncommon, adverse events reported include bleeding, radiologic mediastinitis, peritonitis, and thoracic effusions.[3]

These data offer hope for a new approach to treating these problematic esophageal spastic conditions, which, beyond achalasia, have thus far lacked definitive therapeutic options. The definitive option for achalasia should be discussed with all patients when presenting their therapeutic options. If POEM is chosen, it should be performed in centers of excellence recognized for this procedure.

For patients with achalasia who have long waited for an effective treatment, the future appears to be now.

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Peroral Endoscopic Myotomy (POEM)

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