Antireflux covered metal stent for nonresectable distal malignant biliary obstruction: Multicenter randomized controlled trial

Abstract

Background and Aim An antireflux metal stent (ARMS) for nonresectable distal malignant biliary obstruction (MBO) may prevent recurrent biliary obstruction (RBO) as a result of duodenobiliary reflux and prolong time to RBO (TRBO). Superiority of ARMS over conventional covered self‐expandable metal stents (SEMS) has not been fully examined. Methods We conducted a multicenter randomized controlled trial to examine whether TRBO of an ARMS with a funnel‐shaped valve was longer than that of a covered SEMS in SEMS‐naïve patients. We enrolled 104 patients (52 patients per arm) at 11 hospitals in Japan. Secondary outcomes included causes of RBO, adverse events, and patient survival. Results TRBO did not differ significantly between the ARMS and covered SEMS groups (median, 251 vs 351 days, respectively; P = 0.11). RBO as a result of biliary sludge or food impaction was observed in 13% and 9.8% of patients who received an ARMS and covered SEMS, respectively (P = 0.83). ARMS was associated with a higher rate of stent migration compared with the covered SEMS (31% vs 12%, P = 0.038). Overall rates of adverse events were 20% and 18% in the ARMS and covered SEMS groups, respectively (P = 0.97). No significant between‐group difference in patient survival was observed (P = 0.26). Conclusions The current ARMS was not associated with longer TRBO compared with the covered SEMS. Modifications including addition of an anti‐migration system are required to use the current ARMS as first‐line palliative treatment of distal MBO (UMIN‐CTR clinical trial registration number: UMIN000014784).

Antireflux valve metal stent versus conventional self-expandable metal stent in distal malignant biliary obstruction: a systematic review and meta-analysis

“…6A). Significant heterogeneity was noted (P=0.03, I 2 =72%) among the studies [7-9], best resolved when the study by Hamada et al [8] was excluded, while the new effect estimate showed a significant reduction in the overall incidence of stent dysfunction in favor of the AVRMS group. However, subgroup analysis by cause of dysfunction showed a greater frequency of stent migration (OR 2.76, 95%CI 1.24-6.17; P=0.01; Fig.…”

“…For example, Hu et al concluded that ARVMS significantly reduced the risk of ascending cholangitis and had longer stent patency [7]. On the other hand, Hamada et al showed that ARVMS did not increase the time to recurrent biliary obstruction and was associated with a higher rate of stent migration [8].…”

Intraductal placement of a fully covered metal stent with a long string for distal malignant biliary obstruction without endoscopic sphincterotomy: Prospective multi‐center feasibility study

“…18,19 Conversely, another report did not find any advantage in terms of stent patency, when using anti-reflux valve metal stents. 20 The optimal anti-reflux valve design, including shape, material, and length, remains under investigation.…”

Ways to improve stenting in unresectable malignant distal biliary obstruction: Stent design, intraductal placement, and protective role of an intact papilla?

“…Misra et al reported that free reflux of barium occurred through the SEMSs in all patients in whom the SEMSs were placed across duodenal papilla. To prevent free reflux from the duodenum to the biliary system, several types of SEMSs with anti‐reflux system have been developed 5 . A recent multicenter randomized controlled trial by Hamada et al .…”

“…A recent multicenter randomized controlled trial by Hamada et al . evaluated the superiority of the anti‐reflux metal stent (ARMS) (Niti‐S long‐covered ComVi stent; Taewoong Medical Inc., Seoul, Korea) over conventional CSEMS (Niti‐S ComVi stent; Taewoong Medical Inc.) for SEMS‐native patients with UMDBO 5 . This ARMS had a 7‐mm‐long funnel‐shaped valve made of expanded PTFE, including four 5‐mm‐long longitudinal nitinol wires to maintain its shape.…”