Su1393 A Prospective Multicenter Study of a Fully-Covered Metal Stent in Patients With Distal Malignant Biliary Obstruction: WATCH-2 Study

Abstract

A Prospective Multicenter Study of a Fully-Covered Metal Stent in Patients With Distal Malignant Biliary Obstruction: WATCH-2 Study Shomei Ryozawa*, Hiroyuki Isayama, Iruru Maetani, Yousuke Nakai, Hiroshi Kawakami, Ichiro Yasuda, Hitoshi Mochizuki, Hirotoshi Iwano, Hiroyuki Maguchi, Mitsuhiro Kida, Kensuke Kubota, Tsuyoshi Mukai, Osamu Hasebe, Yoshinori Igarashi, Keiji Hanada, Atsushi Irisawa, Takao Itoi, Kei Ito, Hirofumi Kogure Digestive Disease Center, Showa Univ. Northern Yokohama Hospital, Yokohama, Japan; Gastroenterology, Graduate School of Medicine, The Univ. of Tokyo, Tokyo, Japan; Internal Medicine, Toho Univ. Ohashi Medical Center, Tokyo, Japan; Gastroenterology, Hokkaido Univ. Graduate School of Medicine, Sapporo, Japan; First department of Internal Medicine, Gifu University Hospital, Gifu, Japan; Gastroenterology, Yamanashi Prefectural Central Hospital, Kofu, Japan; Center of Gastroenterology, Teine-Keijinkai Hospital, Sapporo, Japan; Gastroenterology, Kitasato Univ. East Hospital, Sagamihara, Japan; Gastroenterology, Yokohama City Univ. Graduate School of Medicine, Yokohama, Japan; Gastroenterology, Gifu Municipal Hospital, Gifu, Japan; Gastroenterology, Nagano Municipal Hospital, Nagano, Japan; Gastroenterology and Hepatology, Toho Univ. Omori Medical Center, Tokyo, Japan; Center of Gastroenterology, Onomichi General Hospital, Onomichi, Japan; Gastroenterology, Preparatory Office for Aizu Medical Center, Fukushima Medical University School of Medicine, Fukushima, Japan; Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan; Gastroenterology, Sendai City Medical Center, Sendai, Japan Background: We previously reported a longer time to recurrent biliary obstruction with less stent migration (8%) using a new partially-covered nitinol self-expandable metallic stent with flared ends (WallflexTM Biliary RX Partially Covered Stent; Boston Scientific Corp, Natick, Mass) in a multicenter prospective study: WATCH study (Gastrointest Endosc. 2012;76:84-92). A fully-covered type of this SEMS (WallflexTM Biliary RX Fully Covered Stent) is commercially available but there is a concern about the increased risk of stent migration in fully-covered self-expandable metal stents (FCSEMS). Here we conducted a multicenter prospective study of this FCSEMS to evaluate safety and efficacy as well as its removability in patients with distal malignant biliary obstruction. Aim: To evaluate the safety and efficacy of a new, commercially available FCSEMS with flared ends (WallflexTM Biliary RX Fully Covered Stent). Patients and Methods: Between September 2011 and July 2012, 156 patients (112 pancreatic cancer, 64 males, a median age of 75 years old, and median survival time of 196 days) with unresectable distal malignant biliary obstruction underwent FCSEMS placement in sixteen Japanese referral centers. Data on baseline characteristics, survival, stent patency, stent-related complications and removability were prospectively collected. Final analysis at 6 months from the last patient accrual is planned in Feb 2013. Primary endpoint was recurrent biliary obstruction (RBO) and secondary endpoints were technical success rate, stent-related complications and stent removal. Results: Stent placement was technically successful in all patients. The rate of RBO was 28% (stent occlusion, 15% and stent migration, 13%). The cause of stent occlusion was biliary sludge (7%), food impaction (2%), tumor overgrowth (2%) and others (4%). Tumor ingrowth was not observed. Median cumulative time to RBO was 269 (interquartile range: 156-464) days. Other stent-related complications included pancreatitis (6%; mild in 5% and moderate in 1%), cholecystitis (4% of 149 patients with gallbladder in situ) and cholangitis without stent occlusion (3%). Stent removal was successful without complications in all 24 attempted cases (100%) after a median of 120 (range, 3471) days from stent placement. Conclusion: In this interim analysis, WallflexTM FCSEMS appeared comparable to PCSEMS in terms of RBO, but stent migration rate was relatively high. Endoscopic removal is easily and safely accomplished in all 24 attempted cases. (Clinical trial registration number: UMI07131).