Obesity is generally defined as a body mass index (BMI) of at least 30 kg/m2. It affects 30% of the global population and poses a significant healthcare burden. \[1\] Obesity has increased dramatically over the last few decades with over 650 million adults, or 13% of the world's total adult population, meeting diagnostic criteria in 2016.\[1\] In the U.S. the prevalence of obesity increased by 89.9% between 1993 and 2008.\[1,2,3\] As a result, current and potential interventions, and treatment strategies to combat obesity have become more important.
Sleeve gastrectomy, a bariatric surgical procedure, involves resection of the greater curvature of the stomach resulting in more rapid gastric emptying. It has been thought to reduce weight loss by increasing satiation as well as by triggering hindgut mechanisms. These mechanisms include increase in production of certain gut hormones, including GLP-1.\[4\] Sleeve gastrectomy and other bariatric surgeries are very effective at treating obesity, however, only 1% of eligible subjects elect to undergo this treatment option. Additionally, most subjects with obesity do not qualify for bariatric surgery.\[5\]
Endoscopic bariatric and metabolic therapies (EBMT) have recently emerged as alternative treatments for patients with obesity and a BMI over 30kg/m2. Interest in EBMT is growing given their safety, efficacy, and non-invasive nature. Current FDA- approved devices include intragastric balloons (IGB) and suturing devices for endoscopic sleeve gastroplasty (ESG). These gastric interventions work by interfering with gastric accommodation, breakdown and mixing of food, or the antral pump. All of which ultimately impact gastric emptying. IGB are space occupying devices that cause early satiation and must be removed after approximately six months, with subsequent weight regain being an issue. ESG involves endoscopic suturing to reduce the length and width of the stomach to similarly trigger earlier satiation. Delay of gastric emptying has been shown to be a major mechanism of action for both ESG and IGB, and this is also correlated with weight loss, although it is less consistent and well characterized following ESG. \[6\]
ESG is associated with approximately 16% TWL at one year and is well tolerated with a 1-2% SAE rate.\[7\] However, there are several limitations to the procedure in its current form. It is technically demanding with a long learning curve of approximately 50 cases, resulting in few centers offering the procedure, and suture loss is common raising questions of long-term durability.\[8\] There are also numerous suture patterns employed in clinical practice impacting the consistency of results and available suturing platforms are expensive limiting health equity.
The TransPyloric Shuttle (TPS) is a specialized balloon that resides in the gastric antrum and is the only device that incapacitates the antral pump directly impacting gastric emptying. As with other IGB, the TPS must be removed after several months resulting in subsequent weight regain.\[9\]
Gastroplasty with Endoscopic Myotomy (GEM) involves an abbreviated ESG of the gastric body with a pylorus-sparing antral myotomy, adding the TPS mechanism to that of traditional ESG. This employs a modification of the Gastric Peroral Endoscopic Myotomy (G-POEM) technique, targeting the antrum and leaving the pyloric ring intact to slow emptying, instead of making it more rapid. The goal of this procedure is to address the major limitations of ESG, including the procedural variability, technical difficulty, and durability. A small study has shown a consistent delay in gastric emptying with GEM, with the T ½ going from approximately 90 minutes to over 200 minutes, with 20% TWL that continues to trend downward at 6 months. Additionally, there were no new symptoms detected on the Gastroparesis Cardinal Symptom Index (GCSI) score following the procedure.
Although early results suggest the addition of antral myotomy to ESG in the GEM procedure appears to increase weight loss and consistency of delayed gastric emptying, there have been no clinical studies that investigate the efficacy of pylorus sparing antral myotomy alone, without concomitant ESG. However, this approach could have many benefits due to its less invasive nature and relative technical simplicity. There are more endoscopists with the skillset necessary to perform antral myotomy than can perform ESG, and the learning curve would also be substantially shorter. Additionally, the cost of this approach would be considerably lower than current therapies as it only involves an endoscopic procedure, an electrosurgical knife and clips for closure, with no need for an expensive suturing system.
In the proposed study, we will be evaluating the effects of pylorus sparing antral myotomy alone, without concomitant ESG, on weight loss for subjects undergoing the procedure with a history of obesity. This is referred to as Bariatric Endoscopic Antral Myotomy (BEAM). To better understand treatment effects, we will track weight loss, gastric emptying with gastric emptying breath tests (GEBT), and gut hormones (i.e. ghrelin).
This pilot, single-center, randomized, controlled, clinical study aims to assess the safety, tolerability, and short-term efficacy of BEAM, in addition to exploring its impact on gastric physiology. This will also provide data that may be used in designing a larger clinical trial that could be submitted for NIH grant funding.
