Post written by Cyrus R. Piraka, MD, FASGE, from the Henry Ford Health System, Detroit, Michigan, USA.

This study explores whether gastric peroral endoscopic myotomy (G-POEM) could serve as salvage therapy for refractory gastroparesis in patients who had a gastric neurostimulator (GNS) implanted. It was designed as a multicenter, retrospective, 1:2-matched case-control study comparing outcomes of G-POEM in patients who had clinical failure post-GNS with those undergoing G-POEM who never had a GNS implanted.

Gastroparesis has a complex and heterogeneous pathophysiology, with patients experiencing symptoms related in part because of abnormal postprandial proximal gastric accommodation and contraction, reduced frequency of antral contractions, and pylorospasm. GNSs and G-POEM are directed at 2 different targets and produce mixed and inconsistent responses, presumably because of the patient having symptoms related to alternate mechanisms than the 1 that intervention aims to treat.

Unfortunately, it is difficult to identify which mechanism is most relevant to a patient’s symptoms and, therefore, a challenge to prognosticate who will respond to either therapy. Treatment failure is thus an inevitability.

We hypothesized that as G-POEM is aimed at pylorospasm, a mechanism that differs from that targeted by a GNS, patients could receive added benefit from undergoing G-POEM beyond what they receive with a GNS alone.

We researched 123 patients undergoing G-POEM for gastroparesis, 41 who had a prior GNS (cases) and 82 who did not (controls). We found similar clinical results between the 2 groups.

On par with published studies, 65% of all patients had clinical success (defined as a 1 score decrease in the Gastroparesis Cardinal Symptom Index with a ≥25% decrease in at least 2 subscales), and success rates were equivalent between the case (66%) and control (65%) groups.

However, the mean delta improvement in symptoms of bloating and nausea/vomiting, as well as the relative reduction in the use of prokinetic agents, were significantly higher in patients who had a prior GNS. We also found that patients with gastric retention on gastric emptying study (GES) of >25% at 4 hours were about 1.65 times more likely to experience clinical success post-G-POEM.

This study is encouraging in that it demonstrates that G-POEM may provide additive clinical benefit to patients who have had a GNS and may particularly help with symptoms of bloating and nausea/vomiting. However, the study has limitations, including that it is retrospective and prone to selection bias, there was no quality-of-life assessment, pre- and post-G-POEM GES data were incomplete, and GNS settings were not standardized beyond physician judgment; therefore, the definition of GNS failure may have varied somewhat from center to center.

In addition, mean follow-up time was just under 1 year, so we still do not know if salvage G-POEM provides long-term clinical benefit. There also was likely some variation in G-POEM technique from center to center, such as depth of myotomy and whether a single or double myotomy was performed. It is unclear if this would have an impact on outcomes, although controls also were selected from each site.

High-quality prospective studies are needed to confirm the results. It also would be interesting and illuminating to see if GNSs may serve as salvage therapy for G-POEM clinical failures.

I wish to sincerely thank the coauthors, in particular Dr Yervant Ichkhanian, who seems to have boundless energy and has been tireless in his work to advance the field. It has been a privilege to work with everyone on this important study.

Changes in clinical outcomes in terms of Gastroparesis Cardinal Symptom Index (GCSI). GNS, Gastric neurostimulation; G-POEM, Gastric peroral endoscopic myotomy.

Read the full article online.

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