Mo1298 Self-Expandable Metallic Stent With High Axial Force is the Risk Factor of Cholecystitis

Self-Expandable Metallic Stent With High Axial Force is the Risk Factor of Cholecystitis Hiroyuki Isayama*, Kazumichi Kawakubo, Yousuke Nakai, Hirofumi Kogure, Tsuyoshi Hamada, Osamu Togawa, Rie Nagano, Hiroshi Yagioka, Yukiko Ito, Saburo Matsubara, Takashi Sasaki, Natsuyo Yamamoto, Naoki Sasahira, Kenji Hirano, Nobuo Toda, Minoru Tada, Kazuhiko Koike Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Gastroenterology, Japanese Red Cross Medical Center, Tokyo, Japan; Gastroenterology, Kanto Central Hospital, Tokyo, Japan; Gastroenterology, JR Tokyo General Hospital, Tokyo, Japan; Gastroenterology, Tokyo Metropolitan Police Hospital, Tokyo, Japan; Gastroenterology, Mitsui Memorial Hospital, Tokyo, Japan Backgrounds and Aim: Cholecystitis and pancreatitis after biliary self-expandable metallic stent (SEMS) placement are un-resolved serious complications. Our previous retrospective analysis demonstrated tumor involvement to the orifice of cystic duct (OCD) as a risk factor for cholecystitis (Isayama H. Clin Gastroenterol Hepatol. 2006). Subsequently, we reported the measurement of radial force (RF) and axial force (AF), characteristics of SEMSs (Isayama H. Gastrointest Endosc. 2009) and its impact on clinical outcomes including high AF as a risk factor for post-SEMS placement pancreatitis (Kawakubo K. Surg Endosc. 2011 in-press). Here we re-analyzed risk factors for post-SEMS cholecystitis, including radial force (RF) and AF as potential factors to evaluate the impact of SEMS characteristics. Patients and Methods: We retrospectively reviewed consecutive 370 cases who underwent SEMS placement for distal malignant biliary obstruction (356 cases across the OCD) and had gallbladder in situ. Univariate and multivariate analyses of risk factors for post-SEMS cholecystitis were performed. AF and RF of EMSs used in this study are shown in Table 1. We defined high AF as 0.3N and high RF as 4N. Results: SEMSs used in this study were covered in 293 (79%) and with high AF in 241 (65%) cases. Tumor involvement to OCD and gallbladder stones were present in 104 (28%) and 31 (8%) cases, respectively. In total, 26 patients (7%) developed post-SEMS cholecystitis. Multivariate analysis again confirmed tumor involvement to OCD (OR: 5.34, 95%CI: 2.19-13.0, p 0.0001) as a risk factor. In addition, SEMS with high AF (OR: 5.18, 95%CI: 1.69-22.6, p 0.027) and short ( 60mm) SEMS, which is also associated with high AF according to our previous experiments, (OR: 3.20, 95%CI: 1.31-8.67, p 0.010) are significant risk factors of post SEMS cholecystitis. However, the presence of gallbladder stones, covered SEMS and SEMS with high-RF were not risk factors in this analysis. Short SEMSs are associated with higher AF according to our previous experiments in AF measurements. Conclusions: AF significantly influenced the incidences of cholecystitis, as well as pancreatitis, after SEMS placement. The deviation of SEMS from the biliary axis by high AF might cause the compression at OCD, but further evaluation of relation with configuration of the cystic duct is warranted to confirm this hypothesis. Strong emphasis on mechanical characteristics, especially AF, should be given in the future development of SEMS to prevent these complications.