How to prevent and treat biliary lumen-apposing metal stent dysfunction?

Since the development of lumen-apposing metal stents (LAMS), biliary drainage by endoscopic ultrasound guided choledochoduodenostomy (EUS-CDS) has become increasingly popular, thanks especially to its relative simplicity. Initially used as rescue therapy after endoscopic retrograde cholangiopancreatography (ERCP) failure, it is now accepted as first-line treatment in inoperable patients and by expert centers in the latest European guidelines.¹

Indeed, the reported technical success of 88.5–100%, with few adverse effects, has popularized EUS biliary drainage as a more efficient alternative to repeat ERCP or percutaneous transhepatic biliary drainage after failure of a first ERCP.^{2, 3} Initial retrospective observational data have recently been confirmed by two randomized controlled trials (RCTs) that compared EUS-CDS with ERCP, with technical success rates of 90.4% and 96.2% vs. 76.3% and 83.1%, respectively, for ERCP. Although the primary objective of stent patency in those studies did not differ, the contribution of these two publications is essential, as the high technical success rates were obtained by operators who are sometimes nonexperts in EUS-CDS, whereas ERCP, although performed by experts, required an alternative catheterization method, such as a precut, in 40% of cases.^{4, 5}

In view of these results, teams such as ours are considering biliary drainage by EUS-CDS as a first-line procedure for distal tumor obstructions that are operable from the outset in selected patients (with a bile duct greater than 15 mm in diameter) and with no risk factors for stent dysfunction (such as stenosis or duodenal invasion). This alternative, which is just as safe as ERCP and quicker, avoids the risk of acute pancreatitis, which can sometimes delay or even contraindicate curative surgical resection.

Higher costs are currently one of the main factors limiting the already impressive expansion of this technique. However, the development of a competitive market, with the multiplication of devices enabling LAMS EUS-CDS, should logically lead to a reduction in procedure costs.

In view of these factors, it is clear that the number of patients fitted with this type of device will increase, as will the number of patients with LAMS dysfunction. While self-expandable metal stent (SEMS) obstruction and its endoscopic management is now part of the daily routine for interventional endoscopists, LAMS obstructions are a relatively recent problem for which the publication by Vanella et al.⁶ in this issue of Digestive Endoscopy is particularly relevant.

Data on stent patency during follow-up are fairly heterogeneous. The Leuven–Amsterdam–Milan Study Group reported a dysfunction rate of 31.8%.³ A meta-analysis of 201 patients reported a dysfunction rate of 11.5%.⁷ Recently, Fritzsche et al.⁸ reported a rate of 55%, the highest in the literature, in a small prospective series of 22 patients.

Once again, the most robust data come from two RCTs that compared EUS-CDS by LAMS drainage with ERCP, reporting respective dysfunction rates of 8.9% and 9.6% at 1 year, in 150 patients treated with LAMS.^{4, 5}

First, how can we prevent this?

Bile duct diameter less than 15 mm and the presence of a duodenal stenosis were two risk factors for obstruction identified in a multivariate analysis of one of the largest series on this topic.⁹ LAMS compression on the biliary side (type 3a dysfunction) is the probable explanation when the bile duct diameter is less than 15 mm. Adding the increased risk of technical failure into this situation, EUS-CDS with LAMS should probably be avoided in this situation.

With double biliary and duodenal stenosis, performing a double EUS bypass (hepaticogastrostomy and gastrojejunal anastomosis [GJA]) could be the best alternative, as suggested by the CABRIOLET study published by the same team.¹⁰ However, this solution remains technically complex and requires expert operators. If EUS-CDS with LAMS is done, duodenal stenting should be avoided and GJA is required to decrease the risk of food obstruction (type 2b dysfunction) or reflux cholangitis.

The systematic placement of a double-pigtail plastic stent (DPPS) (whose role in treating dysfunction has now been established) within the LAMS to prevent dysfunction is also a potential way to extend the duration of patency, and the results of the Biliary Apposing Metal Pigtail trial will enable us to assess the value of this approach. If the results prove positive, pigtail stent insertion within the LAMS will certainly be generalized, in view of the already highly effective treatment of dysfunction.

Then, how to treat it?

Unfortunately, comparative data by the mechanism of obstruction are not yet available, but the short life expectancy of patients with LAMS may limit the availability of such information.

In conclusion, determining the different mechanisms of obstruction, understanding their mechanisms, identifying risk factors, and studying the best management strategy will be important in the years to come. The relative ease of the procedure must be balanced against the risk of obstruction in the event of incorrect indications, which could impact oncological treatment possibilities. This important article by the Leuven–Amsterdam–Milan Study Group also demonstrates the high technical level required in interventional endoscopy for the management of stent dysfunction, which should not be overshadowed by the relative facility of initial LAMS insertion.⁶

AUTHORS J.A., M.S. and J.J. RECEIVED an honorarium for their lecture from Boston Scientific.

None.