Management of distal malignant biliary obstruction with the ComVi stent, a new covered metallic stent

The covered metallic stent is effective for managing malignant distal biliary obstructions. The most popular covered metallic stent is the covered Wallstent (CWS). This study estimated the efficacy and safety of a new expanded polytetrafluoroethylene (e-PTFE)-covered nitinol metallic stent, the ComVi stent. This covered metallic stent consists of an e-PTFE membrane sandwiched between two uncovered metallic stents with weak axial (straightening) force. Wire is exposed on both the inner and outer surfaces.

Between May 2005 and April 2007, ComVi stents were placed consecutively in 47 patients with unresectable malignant distal biliary obstruction. The cases involved 35 pancreatic cancers, 8 metastatic nodes, 2 gallbladder cancers, and 2 bile duct cancers. The patients were compared with 47 patients who received CWS placement between August 2001 and May 2005 matched for age, sex, and causative disease from 133 cases.

No significant differences in stent patency or patient survival were found. Stent occlusion was observed in 13 patients (27.7%) in the ComVi group and 10 patients (21.3%) in the CWS group. The cause of occlusion in both groups was tumor overgrowth (4.25% vs 4.2%), sludge (8.5% vs 6.3%), impaction of food scraps (14.9% vs 2.1%), and bile duct kinking (0% vs 8.4%). Other complications were migration (2.1% vs 17.0%; p = 0.0304) and cholecystitis (2.1% vs 6.3%), and there were significant differences in the incidence of complications except for occlusion (4.2% vs 24.6%; p = 0.0142).

The ComVi stent has a patency similar to that of the CWS and a lower incidence of migration. However, early occlusion by food impaction was increased and should be resolved.