Walled-off necrosis (WON) is a pancreatic fluid collection, which contains necrotic tissue after four weeks of the onset of acute pancreatitis. Interventions are required to manage patients with infected WON, for which endoscopic ultrasonography (EUS)-guided drainage has become a first-line treatment modality. For patients who are refractory to EUS-guided drainage, the step-up treatment including endoscopic necrosectomy (EN) and/or additional drainage is considered to subside the infection. Recent evidence suggests that EN immediately after EUS-guided drainage may shorten treatment duration without increasing adverse events. In this randomized trial, the investigators will compare treatment duration between EN immediately after EUS-guided drainage versus the step-up approach in patients with symptomatic WON.
Patients with WON defined according to the revised Atlanta classification
The longest diameter of WON is 4 cm or larger
Patients with at least one out of the following conditions; signs of infection, gastrointestinal symptoms, abdominal symptoms, obstructive jaundice
Patients who need drainage for WON
WON inaccessible by EUS-guided approach
AXIOS stent has already been placed into the WON prior to the enrollment
Severe coagulopathy; Platelet count < 50,000/mm3 or prothrombin time international normalized ratio (PT-INR) >1.5
Patients on antithrombotic agents which cannot be managed according to the "guideline for gastroenterological endoscopy in patients undergoing antithrombotic treatment (Dig Endosc. 2014 Jan;26(1):1-14.)"
Parallel
Immediate necrosectomy
Procedure/SurgeryEndoscopic ultrasonography (EUS)-guided drainage will be conducted within 72 hours from randomization. A convex-type echoendoscope is advanced to the stomach or duodenum, and the walled-off necrosis (WON) is visualized and punctured under EUS guidance. A lumen-apposing metal stent (LAMS), such as Hot AXIOS system (Boston Scientific Japan, Tokyo, Japan), is recommended for the initial EUS-guided drainage. For the immediate necrosectomy group, endoscopic necrosectomy (EN) will be performed in the same session of EUS-guided drainage using a gastroscope. The endoscope is inserted into the WON cavity through the LAMS, and necrotic tissue is removed using biopsy forceps, snare, or basket catheter. The EN procedures will be repeated until clinical improvement.
Step-up approach
Procedure/SurgeryEndoscopic ultrasonography (EUS)-guided drainage will be conducted within 72 hours from randomization. A convex-type echoendoscope is advanced to the stomach or duodenum, and the walled-off necrosis (WON) is visualized and punctured under EUS guidance. A lumen-apposing metal stent (LAMS), such as Hot AXIOS system (Boston Scientific Japan, Tokyo, Japan), is recommended for the initial EUS-guided drainage. For the step-up approach group, an additional interventional procedure will be withheld for 72-96 hours after initial EUS-guided drainage. In cases without clinical improvement after 72-96 hours, additional drainage will be permitted, which includes increasing the number of stents, additional EUS-guided drainage, and performing percutaneous drainage (step-up treatment). Insufficient improvement even after two times of step-up treatment allows subsequent endoscopic necrosectomy (EN).
Time to clinical success from randomization
Clinical success is defined as 1) a decrease in the WON size to 3 cm or less and 2) an improvement of more than two out of the three following inflammatory markers; body temperature, white blood cell count, and C-reactive protein.
Adverse events
All procedure-related adverse events including bleeding, perforation, peritonitis, etc.
Mortality
Mortality from any cause
Technical success rate of initial EUS-PCD (Endoscopic ultrasonography-guided pseudocyst drainage)
Successful placement of EUS-guided drainage including a lumen-apposing metal stent and plastic stents
Incidence of biliary and gastrointestinal stricture
Inflammatory-induced obstruction of bile duct and gastrointestinal tract
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