A novel lumen-apposing metal stent with an anti-reflux valve for endoscopic ultrasound-guided drainage of pseudocysts and walled-off necrosis: A pilot study

Background: Pancreatic pseudocysts (PC) and walled-off necrosis (WON) are common complications of severe pancreatitis. Endoscopic ultrasound (EUS)-guided drainage has replaced surgery as the standard treatment for PC/WON. We developed a novel lumen-apposing metal stent (LAMS) with an anti-reflux valve to prevent infectious complications caused by food reflux into the cyst cavity. This retrospective study investigated the efficacy and safety of EUS-guided drainage using this LAMS. Methods: We investigated and compared the treatment outcomes and complications rates between EUS-guided drainage using a novel LAMS (n = 10) versus plastic stents (n = 18) from December 2013 to October 2016. Technical success was defined as successful stent placement without immediate complications. Clinical success was defined as resolution of the PC/WON and disappearance of symptoms. Results: Among 10 patients in LAMS group, 4 patients had complicated PC and 6 patients had WON. In the plastic stent group, 15 and 3 patients had PC and WON, respectively. The median fluid collection size before treatment was 82.5 (interquartile range [IQR], 60.75–118.25) mm and 92.0 (IQR, 75.75–130.25) mm in the LAMS and plastic stent groups, respectively. There were no statistically significant differences in technical success rates (90% vs. 94.4%; p = 0.999), clinical success rates (80% vs. 77.8%; p = 0.999), and complication rates (20% vs. 27.8%; p = 0.999) between the two groups. Conclusions: Treatment outcomes of EUS-guided drainage using a novel LAMS were feasible despite the significantly high proportion of WON. The LAMS allowed acceptable treatment outcomes for EUS-guided drainage.