Seven years later: do we still have an EDGE?Referring to Prakash S et al. pages 52–61
I read with pleasure the systemic review of Prakash et al. on the outcomes, adverse events, and knowledge gaps of endoscopic ultrasound (EUS)-directed transgastric endoscopic retrograde cholangiopancreatography (EDGE) . EDGE was the first example of an EUS-directed entero-enteral anastomosis performed in a human using a lumen-apposing metal stent (LAMS) . While initially met with criticism, EDGE has become accepted as a viable technique to manage pancreaticobiliary disease in patients with Roux-en-Y gastric bypass (RYGB) anatomy. Since its use in EDGE, EUS-guided entero-enteral anastomoses have been expanded to the management of other disease processes, including gastric outlet obstruction and afferent loop syndrome. Despite the increasing popularity of EDGE, a lack of procedural standardization and large-scale generalizable data on its short- and long-term outcomes have hindered its widespread adoption.
Therefore, the analysis of the current literature on EDGE by Prakash et al. is necessary and prudent. I applaud the authors for their extensive search, which led to a final analysis including 169 patients. This number highlights the lack of published data on the EDGE procedure. Unfortunately, despite the authors’ extensive efforts, I fear that there may be some duplication of analyzed cases as multiple authors’ data crossed multiple studies and one author’s data were present in three separate case series.
Despite these limitations, the authors were able to make valuable observations. The most reassuring is that EDGE has a high technical success rate for fistula creation and performance of ERCP, and is similarly effective to laparoscopy-assisted ERCP (LA-ERCP) and superior to deep enteroscopy-assisted ERCP for RYGB patients  . I agree with the authors that early observational data from expert centers likely overestimate the technical and clinical success compared with real-world outcomes.
“Currently, EDGE should likely only be performed at centers with high volume endosonographers with extensive experience in therapeutic EUS and with adequate surgical backup.”
The question then arises, who should be attempting the EDGE procedure? It is clear that more endosonographers with a variety of different training backgrounds are now attempting EDGE, which inevitably leads to a range of outcomes in terms of success and safety. The common denominator however is that, without the proper training, judgment, and safety net from a multidisciplinary system, the endoscopist may be putting indefensible risk on the patient. From a medicolegal standpoint, to perform EDGE, one should have an able and willing surgeon with bariatric experience available at the center to manage potential, time-dependent complications of the procedure, without the need for transfer, and patients should be informed of this surgical availability in their consent process. Currently, EDGE should likely only be performed at centers with high volume endosonographers with extensive experience in therapeutic EUS and with adequate surgical backup.
The authors also concluded that, while the overall rates of major and minor adverse events are acceptable, there is a lack of, and variation in, reporting of adverse events and long-term clinical outcomes in patients undergoing EDGE. The following are some of the pertinent questions that will dominate the evolution of EDGE. Which point of access is superior (gastric vs. jejunal)? Should EDGE be performed in a single-session vs. staged procedure? What diameter LAMS should be used for fistula formation? Should the fistula be closed endoscopically and, if so, by what method? What should be the long-term surveillance of these patients? Some studies have started to scratch the surface of these questions, such as one abstract from a multicenter study that showed transjejunal access may be easier and safer than transgastric access . Others have shown that the vast majority of fistulas close spontaneously or can be managed with minimal endoscopic intervention  .
Ultimately, the goal of EDGE is to be a single-session, single-team, minimally invasive procedure that allows for fistula creation, endoscopic intervention, and fistula closure in a single event. However, because of the inability to endoscopically manage a free perforation on the excluded gastric side and close the index fistula, EDGE is forced to exist as at least a two-stage procedure because LAMS removal requires a second procedure after tract maturation. Until endoscopists can manage this limitation (possibly by a natural office transluminal endoscopic surgery [NOTES] or EUS strategy), the focus should be on minimizing LAMS migration to improve costs, numbers of procedures, and safety.
Undoubtedly, like other therapeutic EUS techniques, the outcomes for EDGE will improve as we study stent size selection, use of lubricants on the endoscope (i. e. mineral oil), and stent securement options. To understand the risk of long-term adverse events, all institutions performing EDGE should have a systematic approach to monitor for chronic fistulas, such as an upper gastrointestinal series at 3–6 months after LAMS removal. Based on these outcomes, the true rate of fistula closure can be determined, with or without any intervention, at the time of LAMS removal, along with the best way to prevent this adverse event from both the safety and cost perspective.
One last point made by the authors that is worth mentioning is the concept of performing LA-ERCP for patients that need concurrent cholecystectomy to perform an “all-in-one” procedure. Currently, our native anatomy patients routinely undergo cholecystectomy and ERCP in separate procedures, by separate teams, in separate procedure suites, via separate routes of access. Now that EDGE has been shown in early studies to be as safe as LA-ERCP, with a shorter procedure time, why should it not be considered to have a similar stand-alone status as ERCP? I surmise that the logistical nightmare of coordinating surgical and endoscopic schedules, significantly increased operating room times, risk of gastrostomy tract formation, and the need for possible 30-Fr gastrostomy tube placements in patients with the need for subsequent ERCP raises the argument that, regardless of cholecystectomy status, EDGE may still be the optimal option for all parties involved.
Only time will tell, and more high quality data are needed to answer many of these questions. EDGE has come a long way since its inception, when it was immediately met with significant criticism and skepticism . However, as more EDGE procedures are being performed by interventional endoscopists around the world who are gaining competency and comfort with the technique, and outcomes continue to be relatively effective, safe, and cost-efficient, it seems that even the early critics of EDGE have become adopters and have attempted to rebrand it in their own practices. Together, with high quality, forthright reporting of outcomes, we can continue to standardize the performance of EDGE and its outcomes, so that it can solidify its place in the treatment algorithm for RYGB patients.
05. August 2021 (online)
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