Plastic stents: silenced by the LAMS?

I well remember the first time I deployed a lumen-apposing metal stent (LAMS). It was about a decade ago and I went to a demonstration of the new technology sponsored by the stent manufacturer at a national gastroenterology meeting. After a brief instructional tutorial and using a plastic cyst model, I successfully deployed the stent in what I remember being about 30 seconds. Among the many takeaways from that experience was that this new disruptive technology would soon render the standard laborious cystenterostomy technique obsolete.

Since the first series on endoscopic cystenterostomy with debridement of walled-off pancreatic necrosis (WON) published by Baron et al. in 1996 until the use of LAMSs became widespread, endoscopic cystenterostomy was practiced by relatively few therapeutic endoscopists [11]. Creating a cystenterostomy – endoscopic ultrasound-guided cavity puncture and wire placement, followed by serial dilation, beginning with the fine-needle aspiration needle sheath and progressively dilating, using biliary dilators and through-the-scope balloons, up to 20mm – was technically challenging. The possibility for misadventure was high, and initially complications including free perforation and bleeding were not uncommon [22]. In addition, once the cystenterostomy had been created, multiple options for debridement remained – the type and number of plastic stents, timing of first debridement, varying necrosectomy techniques, and timing of return procedures, among others.

Moving forward, trials studying lumen-apposing metal stents must continue to address questions such as patient selection (size and location of walled-off necrosis, degree of necrosis) and intervention (debridement tools, number of stents), and the definition of treatment success (complete cavity resolution, avoidance of surgery, etc.) must be standardized.

LAMSs were revolutionary because they lowered the technical expertise needed to perform cystenterostomy safely, and so their use became more widespread. As a result, the laborious means of creating a cystenterostomy the “old fashioned way” fell by the wayside as LAMS placement became universally adopted. However, despite the widespread use of LAMSs, most of the controversies with regard to debridement remained, and comparative effectiveness studies evaluating plastic stents vs. LAMSs were initially limited.

In this issue of Endoscopy, Bang et al. publish their meta-analysis evaluating the clinical outcomes of patients in three randomized trials comparing LAMSs vs. plastic stents for the treatment of WON [33]. Among 206 patients, they found that, except for the duration of the procedure, there was no difference in the important clinical outcomes, such as need for necrosectomy, number of interventions, treatment success, or recurrence. In addition, adverse events and costs were similar between the groups.

On the surface, these findings support the initial impressions I had a decade ago, when I had my first exposure to LAMSs: rapid, safe, and successful – cystenterostomy for the masses – and certainly a disruptive improvement over the tedium and risk of plastic stent placement. Given the choice between plastic stents or LAMSs to create a fistula tract, it seems pretty clear now that a LAMS is the better choice.

However, this meta-analysis does not answer many of the more pressing questions that still confound those of us facing dense WON, often in the context of a disrupted pancreatic duct, because the studied patients had highly variable types of collections. Any therapeutic endoscopist who treats such patients frequently knows the difference between “nasty” WON – large collections that are mostly solid and require multiple debridements – and those collections that are easily managed by evacuating with some simple flushing in one sitting. The treatment is very different, as are the expectations for success. To support this point, only slightly more than half of the patients had necrosis >30% (one included study did not report this critical characteristic); less than half required a necrosectomy. One study did not even report the outcome of treatment success and a strong surrogate marker for endoscopic failure – the need for surgical intervention – was as high as 15% in one of the LAMS study groups.

So while this meta-analysis supports that LAMSs are faster than plastic stents in creating the therapeutic cystenterostomy window, the heterogeneity of the included patients and the lack of study-specific reported outcomes unfortunately does not allow us to conclude too much more, leaving many questions remaining. For example, we still don’t know if a plastic stent should be placed through the LAMS to prevent stent occlusion, if placing multiple plastic stents at the index endoscopy indefinitely (“one and done” technique) is more effective than serial debridement, or if new debridement tools will be effective in reducing repeat procedures.

Moving forward, comparative effectiveness trials studying WON must continue to address some of these questions. To do this effectively, patient selection (size and location of WON, degree of necrosis) and intervention (debridement tools, number of stents), and the definition of treatment success (complete cavity resolution, avoidance of surgery, etc.) must be standardized in further studies. LAMSs for WON have revolutionized our ability to create cavity access easily, quickly, and safely. But has this meta-analysis proven that plastic stents for WON have now been completely silenced by the LAMS? My belief is not quite yet, with the hope that continued investigation will foster management clarity for this complicated disease.

Publication History

Article published online:
17 January 2024

• References

• 1 Baron TH, Thaggard WG, Morgan DE, Stanley RJ. Endoscopic therapy for organized pancreatic necrosis. Gastroenterology 1996; 111: 755-764 DOI: 10.1053/gast.1996.v111.pm8780582. (PMID: 8780582)
• 2 Gardner TB, Coelho-Prabhu N, Gordon SR. et al. Direct endoscopic necrosectomy for the treatment of walled-off pancreatic necrosis: results from a multicenter U.S. series. Gastrointest Endosc 2011; 73: 718-726
• 3 Bang JY, Wilcox CM, Navaneethan U. et al. Treatment of walled-off necrosis using lumen-apposing metal stents versus plastic stents: a systematic review and meta-analysis of data from randomized trials. Endoscopy 2023; DOI: 10.1055/a-2169-0362.