Research Progress of Bariatric Embolization for Treatment of Obesity
Obesity, defined as a body mass index (BMI) of 30 kg/m² or higher, is a growing global health concern. It is a significant risk factor for numerous chronic diseases, including diabetes, cardiovascular disorders, and certain cancers. Traditional treatments for obesity include lifestyle interventions (such as diet and exercise), pharmacotherapy, endoscopic bariatric therapies, and bariatric surgery. However, for patients who fail to achieve weight loss through lifestyle changes and are not candidates for surgery, treatment options are limited. Bariatric embolization (BAE), a minimally invasive procedure performed by interventional radiologists under imaging guidance, has emerged as a promising alternative.
Mechanism of Bariatric Embolization
BAE targets the blood supply to the gastric fundus, where approximately 90% of ghrelin, a hormone that stimulates appetite, is produced. By embolizing the left gastric artery (LGA) and, to a lesser extent, the gastroepiploic artery (GEA), BAE induces ischemia in the gastric fundus, thereby reducing ghrelin production. This reduction in ghrelin levels helps control appetite and, consequently, body weight. Obese individuals often fail to suppress ghrelin levels after eating, leading to overeating. BAE addresses this issue by disrupting the ghrelin-producing cells, offering a novel approach to weight management.
Early Animal Studies
The concept of BAE was first explored in animal studies. Arepally et al. conducted the initial study, demonstrating that ghrelin levels could be significantly altered by embolizing the gastric artery using morrhuate sodium. Subsequent studies in growing swine and obese dogs further supported these findings, showing a decrease in serum ghrelin levels and either increased absolute weight loss or reduced weight gain compared to control groups. These early studies laid the groundwork for clinical investigations into BAE.
Clinical Investigations
Clinical data on BAE is still limited, but the results so far are promising. Gunn and Oklu, as well as Anton et al., published retrospective studies in 2014 and 2015, respectively, reporting preliminary positive outcomes in terms of treatment efficacy and safety. Following these, three prospective studies were conducted, all of which demonstrated promising short-term efficacy and safety.
Ongoing Clinical Trials
Currently, there are two ongoing clinical trials focusing on BAE, both of which have published preliminary results. The first is the Bariatric Embolization of Arteries for the Treatment of Obesity (BEAT Obesity) trial conducted by Weiss et al. at Johns Hopkins Hospital in the United States. This study enrolled five severely obese patients (four women, one man) with a mean BMI of 43.8±2.9 kg/m². The results showed no major adverse events (AEs). At the 1-month follow-up, there was a 5.9% excess weight loss, which increased to 9.0% at the 3-month follow-up. Mean fasting serum ghrelin levels showed minimal changes from baseline at weeks one and two, with an 8.7% increase at 1 month and a 17.5% decrease at 3 months. These findings suggest that BAE is safe and potentially effective for treating obesity.
The second ongoing trial, conducted by Bai et al. in China, included five obese patients with a mean BMI of 38.1 kg/m². No serious AEs were observed. The mean body weight loss at 3, 6, and 9 months post-BAE was 8.28 kg, 10.42 kg, and 12.90 kg, respectively, indicating continuous weight loss during the follow-up period. Serum ghrelin levels decreased by 40.83%, 31.94%, and 24.82% at 3, 6, and 9 months, respectively. Similar to the BEAT Obesity trial, this study demonstrated the safety and potential efficacy of BAE.
Updated Results and Long-term Outcomes
Weiss and Teng presented updated 1-year outcomes from their studies at international academic meetings in 2018. The intermediate results from both ongoing trials showed positive and promising outcomes in terms of safety and efficacy. Compared to bariatric surgery and endoscopic therapies, BAE resulted in lower mean excess weight loss (up to 30% vs. about 10%) but appeared to be safer, with fewer complications. However, slight weight regain was observed at the 1-year follow-up compared to earlier time points (6 and 9 months), raising questions about the need for repeat embolization or supplementary treatments such as banding or pharmacology.
Key Questions and Future Directions
Several key questions need to be addressed before BAE can become a widely accepted treatment for obesity. First, the ideal candidate for BAE remains unclear. The BMI of patients in the GET LEAN and BEAT Obesity trials was no less than 40 kg/m², while the Chinese trial included patients with a BMI of at least 30 kg/m². The results suggest that BAE may be more effective in treating obese but not severely or morbidly obese patients.
Second, the impact of BAE on diabetes is an area of interest. Preliminary observations from the GET LEAN and BEAT Obesity trials showed a clinically significant effect on one patient and a general reduction in HbA1c levels, respectively. Further studies with larger sample sizes are needed to explore this potential benefit.
Third, the standard technique for performing BAE has yet to be established. Different embolic agents and vessel targets have been used in previous studies. The LGA is the most common target, but the BEAT Obesity trial also included the distal GEA if it was a significant source of fundal perfusion. Standardizing the procedure will be crucial for ensuring consistent outcomes.
Conclusion
Bariatric embolization represents a promising minimally invasive option for treating obesity, particularly for patients who do not qualify for surgery. Early clinical trials have demonstrated its safety and potential efficacy, with significant weight loss and reduced ghrelin levels observed in patients. However, further research is needed to address key questions regarding patient selection, long-term outcomes, and the impact on comorbid conditions such as diabetes. Standardizing the procedure and exploring supplementary treatments will be essential for optimizing the benefits of BAE. As the field continues to evolve, BAE has the potential to become a valuable tool in the fight against obesity.
doi.org/10.1097/CM9.0000000000000155
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