G-POEM: Hope

This is half of a two-part debate — read the opposing argument. The opinions expressed here are that of the author and do not represent the position of AGA.

Gastroparesis is a chronic and debilitating disorder with a complex pathophysiology yet to be fully understood. Unfortunately, the incidence of gastroparesis and the hospital stays associated with it have been increasing in the U.S. during the past decade. Treatment options are limited, and metoclopramide is the only medication approved by the U.S. Food and Drug Administration for this disabling condition. Treatment success rates are disappointing, even in tertiary centers, leading to frequent visits to the emergency department (ED) and hospital stays.1,2

Also known as peroral endoscopic pyloromyotomy, gastric peroral endoscopic myotomy (G-POEM) is a novel, minimally invasive, flexible endoscopic procedure that is emerging as a new treatment option for select patients with refractory gastroparesis. Pyloric-directed therapies, such as surgical pyloroplasty and pyloric stenting, in open-label and retrospective reports were shown to improve symptoms of gastroparesis. Thus, G-POEM emerged as an extension to these pyloric-directed therapies.

The procedure has gained popularity due to its exciting potential in a debilitating disease for which available therapeutic options are quite limited. Early experience in the U.S. and Europe showed good clinical response rates. Overall, the clinical response rate, as determined by symptomatic improvement, following G-POEM reached 73 to 86 percent after up to 12 months of follow-up.1,3-5 The overall complication rate of G-POEM is low, ranging from 0 to 6.7 percent. Available data suggest that it improves symptoms of gastroparesis (measured by an improvement in the Gastroparesis Cardinal Symptom Index [GCSI]), improved quality of life (as measured by an improvement in 36-Item Short Form Health Survey score) and decreased gastric emptying time during short- and mid-term follow-up in as many as 70 percent of patients. Serious adverse events have been rare but have included gastrointestinal bleeding, pyloric ulcer and tension capnoperitoneum.1,2,5 The long-term effectiveness of G-POEM is still unknown. We suggest the following two selection criteria for G-POEM: an average GCSI score larger than two and gastric retention at four hours of more than 20 percent. As more data become available, it will be important to identify a specific patient population who would benefit most from this novel procedure. The big question would then be: Where do we place G-POEM in the treatment algorithm? Do we consider it only in patients with refractory gastroparesis or in those with early gastroparesis?

The procedure is technically feasible and safe, and, in the hands of an experienced specialist, it has a low risk of complications. However, it is a technically challenging procedure compared with esophageal peroral endoscopic myotomy due to antral contractions, curved submucosal tunnel, extensive vascularity and a very thin duodenal wall, which predisposes patients to a high risk of perforation.

We started performing G-POEM in 2015 and have now established a very successful G-POEM program. As part of a major tertiary center, we have a high referral rate for patients with gastroparesis. We offer G-POEM to patients with refractory gastroparesis whose predominant symptoms are nausea and vomiting. We do not offer G-POEM for patients whose predominant symptoms are abdominal pain and bloating. In our opinion, patients taking long-term narcotic therapy and those with end-organ damage due to long-term diabetes are not ideal candidates for the procedure because they are unlikely to benefit from it.

Gastroparesis is a heterogeneous disorder, and not all patients with gastroparesis will have pyloric dysfunction. Thus, not all patients will benefit from G-POEM. Therefore, we strongly advocate for the use of pyloric diagnostic techniques such as impedance planimetry. Impedance planimetry is a novel tool for assessing pyloric distensibility and compliance, and it could potentially be used to identify a subgroup of patients for whom endoscopic techniques for pyloric-directed therapies could be utilized.

Compared with surgical pyloroplasty, G-POEM is more appealing to patients because it is a minimally invasive endoscopic procedure — no need exists for an invasive surgical procedure — and it provides shorter lengths of hospital stays and is a less painful procedure. In addition, the cost of the procedure will be significantly lower. As we make steady progress in the field of G-POEM, it is important to acknowledge that these results were derived from small retrospective studies. Although large, prospective, randomized trials are needed, several limitations exist because a gold standard does not exist to which the effectiveness of G-POEM can be compared. Gastric-emptying scintigraphy is the only objective testing with symptoms for all patients with gastroparesis.


With only 100 or so cases described in the medical literature and no consensus on outcomes, G-POEM is unarguably an experimental procedure with the potential to permanently alter gastric anatomy with unknown consequences.


Logistically, a sham-controlled trial would not be possible to perform. The procedure will become widely acceptable if results from earlier studies are reproducible and the procedure shows long-term effectiveness in maintaining symptomatic improvement. Thus, more robust data are needed on its long-term outcomes and safety, refining the procedural technique and demonstrating benefit from an economic perspective.

We strongly believe that G-POEM is a viable treatment option for a subset of patients with gastroparesis refractory to medical therapy. Ideally, it should be performed by an experienced endoscopist in a research setting. The procedure should be performed under an approved protocol only. Currently, the ideal patient population and long-term outcomes are unclear, thus should not be performed in the clinical setting yet. It should be offered to patients with nausea and vomiting as the predominant symptoms.

Concomitant gastric electrical stimulation can be performed in select patients with nausea-predominant diabetic gastroparesis. Pyloric diagnostic techniques such as impedance planimetry or a wireless capsule motility should be performed when available to determine the appropriate candidates for G-POEM. Our goal is to provide symptomatic relief for this group of patients with limited treatment options, and, in turn, decrease their need for supplemental nutrition, medications, ED visits and hospital stays.

Key takeaways

  • G-POEM is a safe and effective treatment for select patients with refractory gastroparesis.
  • G-POEM should be offered to patients in the research setting who present with nausea and vomiting as their predominant symptoms. It does not benefit patients with abdominal pain or bloating.
  • Clinical outcomes of G-POEM in short and mid-term studies are promising and consistent in all of the reported retrospective studies.
  • No parameters currently identify target patients for G-POEM, and no factors reliably predict a patient’s clinical response to G-POEM.

Dr. Cai has a retainer agreement with Boston Scientific, Aries Pharmaceuticals, and Microtech, and has given lectures for Aries Pharmaceuticals. Dr. Cai is the current president for Georgia Gastroenterologic and Endoscopic Society. Dr. Dacha has no conflicts to disclose.


Dr. Pankaj Jay Pasricha describes G-POEM as an unarguably experimental procedure.


References
1. Khashab, M.A., Ngamruengphong, S., Carr-Locke, D., et al, Gastric per-oral endoscopic myotomy for refractory gastroparesis: results from the first multicenter study on endoscopic pyloromyotomy (with video). Gastrointest Endosc. 2017;85:123-128.
2. Mekaroonkamol, P., Dacha, S., Wang, L., et al, Gastric per oral endoscopic pyloromyotomy reduces symptoms, increases quality of life, and reduces healthcare usage with gastroparesis. Clin Gastroenterol Hepatol. 2018. [Epub ahead of print].
3. Malik, Z., Kataria, R., Modayil, R., et al, Gastric per oral endoscopic myotomy (G-POEM) for the treatment of refractory gastroparesis: early experience. Dig Dis Sci. 2018. [Epub ahead of print].
4. Dacha, S., Mekaroonkamol, P., Li, L., et al, Outcomes and quality-of-life assessment after gastric per-oral endoscopic pyloromyotomy (with video). Gastrointest Endosc. 2017;86:282-289.
5. Gonzalez, J.M., Lestelle, V., Benezech, A., et al, Gastric per-oral endoscopic myotomy with antropyloromyotomy in the treatment of refractory gastroparesis: clinical experience with follow-up and scintigraphic evaluation (with video). Gastrointest Endosc. 2017;85:132-139.

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