Bariatric Embolization Trial for the Obese Nonsurgical

Since 2003, the proportion of Canadians who were obese has increased 17.5%. Obesity is ranked as the fifth leading risk for mortality globally. Obesity has been strongly linked to numerous comorbidities, including type II diabetes, hyperlipidemia, hypertension, obstructive sleep apnea, heart disease, stroke, asthma, cancer, and depression.

The pathophysiology of obesity is complex and inadequately understood. Nevertheless, an energy imbalance is fundamentally at fault. As recently as 1996, ghrelin, the hormonal stimulus for hunger was identified. Further research has revealed that ghrelin, predominantly produced in the fundus of the stomach, stimulates appetite and increases serum concentrations of growth hormone, adrenocorticotropic hormone, cortisol, prolactin, and glucose.

Congruously, the complexity of obesity is reflected in the efficacy of modern therapy. Treatment for obesity lies along a spectrum of available modalities beginning with diet modification, exercise therapy, pharmacotherapy, and surgery. Despite initial positive results, diet and exercise frequently prove futile for long-term management of weight loss. Likewise, it is uncommon for diabetic remission to be achieved through pharmaco-therapeutic agents, most of the medications designed to stabilize and improve diabetic control. This has led to the advent of interventional treatment for these conditions.

Bariatric surgery is the current gold-standard in the treatment of morbid obesity with recent evidence revealing that bariatric surgery is more effective than medical treatment for the long-term control of obese patients with type 2 diabetes. It is postulated that in addition to the restrictive effects associated with bariatric surgery, resection or disruption of the ghrelin producing regions of the stomach may play a significant role in eventual weight loss.

The primary source of blood flow to the fundus of the stomach, where the majority of ghrelin-producing cells are found, is the left gastric artery. This artery is commonly accessed percutaneously for the management of refractory upper gastrointestinal bleeding. Embolizations are typically well tolerated, therefore, it has been purported that selective embolization of this artery could induce adequate ischemia to the fundus resulting in a rapid decrease in ghrelin-producing cells along with its neurological and metabolic effects.

In 2007, Arepally et al reported a minimally-invasive method of destroying ghrelin-producing cells in a porcine model. With mixed success, Arepally was able to demonstrate a correlation between left gastric artery embolizations, weight loss, and fluctuations in ghrelin levels. Propagation of his efforts was performed by Bawudun et al, utilizing a liquid sclerosant and 500-700-mm polyvinyl alcohol (PVA) particles as embolic agents, Bawudun was able to demonstrate significant decreases in ghrelin and body weight measurements in the experimental arms in a canine model. Subsequently, Paxton, et al. demonstrated lowered ghrelin levels and reduced weight gain utilizing 40-micron microsphere particle embolizations in a similar porcine model no duodenal upregulation for ghrelin was found. These studies also revealed potential complications including non-target embolization, frank gastric ulcerations, and gastritis.

Following these preclinical animal studies, Gunn and Oklu performed a small retrospective study of patients who underwent a left gastric artery embolization for upper gastrointestinal bleeds. The results, although limited, revealed significant weight loss amongst the experimental group as compared with the control (patients who underwent embolization for upper gastrointestinal bleeds without left gastric artery selection). Kipshidze et al reported significant weight loss amongst all five patients who underwent the first-in-human prospective left gastric artery embolization trial utilizing 300-500 µm microspheres. Human trials have resulted in few reported complications, namely minor pyrosis and indigestion. The safety profile of the procedure is well reported given that elective left gastric artery embolizations are offered to stable patients with refractory non-variceal bleeds. Case reports have reported on the uncommon instances of hepatic infarction, gastric infarction, gastric volvulus, and arterial rupture.

The momentum behind this procedure has led to the design and implementation of two phase I clinical trials [Gastric Artery Embolization Trial for the Lessening of Appetite Nonsurgically (GET LEAN) and Bariatric Embolization of Arteries for the Treatment of Obesity (BEAT Obesity)] which sought to demonstrate the safety profile of left gastric artery embolizations and demonstrate post-procedural weight loss.

Results have been promising with weight loss and safety demonstrated in both trials.

Minor complications included post-procedural nausea, vomiting, and mild epigastric discomfort which was treated with oral proton pump inhibitors (PPIs) following administration of one course of intravenous (IV) PPIs. 3 asymptomatic gastric ulcers were identified on post-procedural endoscopy however these resolved within 1 month (a 1-month endoscopy was performed).