• ACUTE PANCREATITIS
• PANCREATIC PSEUDOCYST
• ENDOSCOPIC RETROGRADE PANCREATOGRAPHY

With interest we read the paper by Bang et al,1 who observed delayed severe adverse events after endoscopic treatment of pancreatic fluid collections (PFCs) with the Hot AXIOS lumen-apposing metal stent (LAMS), which was unrelated to the initial procedure, in a randomised controlled trial. LAMS are increasingly used for transmural endoscopic ultrasound-guided drainage of PFC and infected walled-off pancreatic necrosis (WOPN).2 Procedure associate bleeding is a frequent adverse event after transmural drainage.3 While our experience confirms our colleagues' findings we would like to emphasize that complications are not restricted to Hot AXIOS stents and that certain insertion techniques may be more prone to early bleeding while non-pigtail, LAMS can cause late bleeding complications.

From June 2013 to October 2016, we treated 46 patients with LAMS (8×Hot AXIOS 15×10 mm (Boston Scientific); 38×TAEWOONG MEDICAL Niti-S biliary covered stent (NAGI) 10.5F 14×20 mm) for infected WOPNs. The overall 90-day mortality of our 46 patients was 8.7%, median APACHE score at intervention was 17. Bleeding complications occurred in eight patients (17.4%) (figure 1), five of which suffered from multiorgan failure (table 1). Two of these patients died because bleeding persisted after unsuccessful coiling and surgery (two out of eight, 25%). Seven of these patients received treatment with NAGI-S stents and one patient was treated with a Hot AXIOS stent. In three cases treated with NAGI-S stents, the GI bleeding occurred within the first 24 hours after LAMS placement leading to haemorrhagic shock controlled by conservative measures. In these cases, balloon dilatation of the access route had caused injury to gastric veins. In five patients we observed delayed bleeding into the necrotic cavity over a period of up to 5 weeks after LAMS placement (62.5% of bleeders or 11% of all patients treated with LAMS). The mean time from LAMS placement to bleeding was 9.5±9.8 days (2.7; 16.3). In 3 of the 48 patients the metal stent dislocated. However, in all cases stent removal was achieved endoscopically without further complications. One patient suffered from visceral organ perforation by the stent without the need for surgery. In our series we did not observe other severe adverse events such as buried LAMS syndrome or biliary strictures.

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Figure 1

Scatter plot showing timing and incidence of bleeding complications following lumen-apposing metal stent (LAMS) treatment over time.

The high rate of early bleeding complications in patients receiving the Niti-S biliary covered stent seems to be caused by the different placement procedure. For the placement of the Niti-S stent, the stomach wall is dilated with a balloon catheter to up to 8 mm over a guide wire causing early bleeding. Five of our patients suffered from multiorgan failure and, even in the absence of coagulopathy, this seems to be a risk factor of its own—while being an indication for draining an infected necrosis in the first place. Of note, 80% of our patients with delayed bleeding events needed angiographic intervention of the left gastric artery. As coiling of the left gastric artery very rarely induces necrotic changes to the stomach prophylactic coiling in high-risk patients (persistent multiorgan failure, coagulopathy and metabolic acidosis) in whom LAMS are kept in place for more than 21 days should be prospectively studied. Exchanging LAMS for plastic pigtail stents before hospital discharge of a patient with LAMS drainage of WOPN may be even more feasible and could reduce late bleeding. Diffuse late bleeding often occurs in patients with a nearly clean necrotic cavity, in the absence of signs of systemic inflammation and after a final mechanical cleansing of the cavity. How complete the removal of the necrotic debris from a WOPN should be remains a point for further investigation.