How trivial is lumen-apposing metal stent retrieval?

Lumen-apposing metal stents (LAMSs) were originally conceived for transgastric or transduodenal endoscopic drainage of symptomatic pancreatic pseudocysts and walled-off necrosis (WON). Their inner diameter is large enough to allow direct endoscopic necrosectomy, and their wide flanges on both ends provide an effective anchorage with lower rates of migration. “Hot LAMS” systems are enhanced with an electrocautery tip that allows fast and easy stent delivery, and limits the use of ancillary tools and fluoroscopy. Many off-label indications for LAMSs have emerged, notably for endoscopic ultrasound (EUS)-guided biliary drainage, when endoscopic retrograde cholangiopancreatography fails or is not feasible [1]. Although the US Food and Drug Administration has approved a 60-day maximum stent indwell time, longer and sometimes permanent stent placements are performed, especially in patients with malignant disease. Overall, the decision to retrieve a LAMS and the timing of this should be part of a global strategy.

A first prospective cohort of LAMS procedures for pancreatic fluid collections (PFCs) reported easy, successful and uneventful stent removal after a median (range) indwell time of 32 (2–178) days in all 47 patients for whom retrieval was indicated [2]. Concerns about the timing of LAMS retrieval were raised in 2017, when Bang et al. warned of an excessive rate of severe adverse events (SAEs) in the interim audit of a monocentric trial comparing LAMSs to plastic stents for WON drainage. Among 12 patients randomized to the LAMS group, three had presented with severe bleeding due to pseudoaneurysms (at weeks 3–5 post-placement) and two were found to have buried stents at the endoscopy that was scheduled for their removal (at weeks 5 and 6) [3]. The authors hypothesized that LAMS immobility favors mucosal overgrowth and friction with surrounding neovessels, whereas, conversely, double-pigtail plastic stents are mobile and gravitate towards the digestive lumen as the PFC resolves. Consequently, the 2018 ESGE guidelines [4] strongly recommended – with low quality evidence – LAMS retrieval within 4 weeks post-PFC drainage.

Of note, after the amendment of the randomized trial by Bang et al. where a CT scan was performed at 3 weeks to assess WON resolution before subsequent stent retrieval, AE rates were similar in the LAMS and plastic stent groups (6.5 % vs. 6.9 %) [5]. Since then, data regarding AEs related to LAMS removal following drainage for PFCs have accumulated [6], and two recent high quality studies have brought new insights on the matter.

In 2022, an 18-center, 5-year retrospective study was conducted in the UK and Ireland, collecting data from 1018 patients with “hot LAMS” PFC drainage (539 WONs, 479 pancreatic pseudocysts). LAMS removal was attempted after a median time of 7 weeks, and beyond week 4 in 687 patients (80.2 %). Significant delayed bleeding and a buried stent occurred in 1.9 % and 4.7 % of patients, respectively. No relationship with any risk factor (including indwell time) was found [7].

“First, “hot LAMS” may be preferred to “cold LAMS” to prevent complex removal being required. Second, the putative effect of coaxial pigtail stent placement within LAMSs to prevent severe bleeding at the time of LAMS removal is not demonstrated. Third, LAMS removal seems highly feasible, technically straightforward, and safe. Fourth, a longer stent indwell time (possibly 6 weeks or longer) can be considered.”

In this issue of Endoscopy, Bazaga et al. report on a 1-year prospective data collection for 407 LAMS placements from a Spanish multicenter register [8]. The indications for LAMS placement were varied: WON (n = 76), pancreatic pseudocysts (n = 39), non-PFC drainage (n = 19), EUS-guided gastroenteroanastomosis (n = 17), EUS-guided gallbladder drainage (n = 4), EUS-guided choledochoduodenostomy (n = 2), and post-surgical anastomotic dehiscence (n = 1). Removal was attempted in 158 patients, with a median indwell time of 6.6 weeks. There were 13 stents (8.2 %) that were partially or totally embedded. All 158 LAMSs were successfully removed, at first attempt in 156 procedures (98.7 %). The median removal time was 2 minutes. Removal was complex for 13 LAMSs (8.2 %), according to a composite endpoint (when stated “[very] difficult” by the operator, and/or with a procedural duration of > 10 minutes).

The most striking finding of the study is that the stent embedment rate was significantly lower in the group with an indwell time < 6 weeks (3.1 %), compared with those with indwell times of 6–12 weeks (15.9 %) and ≥ 13 weeks (23.3 %). Stent embedment and the over-the-wire technique (“cold LAMS”) were independent risk factors for complex retrieval, whereas stent indwell time was a confounding factor. A total of eight AEs (7 bleeds, 1 cholecystitis) were reported at the time of LAMS retrieval, with none of these being severe. Coaxial double-pigtail plastic stents were not associated with lower rates of embedment, complex removal, or AEs.

Overall, this prospective case series is the largest to date specifically assessing LAMS removal and demonstrates how often LAMS retrieval is a trivial procedure. Its results, together with those of the recent large, but retrospective, UK and Ireland series, suggest changes in our standard-of-care protocols in several areas. First, “hot LAMS” (when appropriate) may be preferred to “cold LAMS” to prevent complex removal being required. Second, the putative effect of coaxial pigtail stent placement within LAMSs to prevent severe bleeding at the time of LAMS removal is not demonstrated. Third, LAMS removal seems highly feasible, technically straightforward, and safe, not only for PFC treatment, but also for biliary drainage. Fourth, both studies allow reconsideration of a longer stent indwell time (possibly 6 weeks or longer). This is of tremendous importance as some patients with WONs require repeated sessions of direct endoscopic necrosectomy, beyond the initial 4-week period, while other patients face delayed appointments in stretched healthcare systems.

In summary, both recent studies show that LAMS removal is safe and simple enough to be performed in nonexpert centers for the many patients with a low risk profile (within 6 weeks following the “hot LAMS” placement technique), with favorable evaluations on CT scan (no pseudoaneurysm, collapsed PFC) and endoscopy (no significant stent ingrowth or overgrowth). For today’s endoscopist, LAMS insertion is quite attractive, but their retrieval seems to be even more seductive!

Publication History

Article published online:
03 May 2023

• References

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