Theoretical advantages of stent do not reflect reality

The Biliary Wallstent from Boston Scientific has been used for a decade for palliation of malignant obstructive jaundice. Although the newer Luminexx from German vendor Angiomed offers several theoretical advantages, researchers in the U.K. have found that those advantages do not hold up under close scrutiny.

The self-expanding Wallstent is made of a braided cobalt-based monofilament that is inserted via a 7-F delivery system. The stent shortens distally as it expands, according to Dr. Shuvro Roy-Choudbury, who presented the study on Sunday.

The Luminexx, also self-expanding, is composed of a contiguous nitinol tube that is laser-cut to allow flexibility and expansion. It is inserted via a 6-F delivery system and does not shorten.

Between May and December 2002, interventionalists at Hull and Yorkshire Hospitals in the U.K. inserted 55 Wallstents in 46 patients and 29 Luminexx stents in 25 patients. In both groups, obstruction was due mainly to pancreatic cancer and metastases, and the majority of strictures occurred in the distal common bile duct.

Mean patient survival was 157 days in the Wallstent group and 132 days in the Luminexx group. Four of 46 Wallstents occluded on follow-up after a mean period of 98 days; three of the occlusions were due to tumor ingrowth. Eight of 26 Luminexx stents blocked after a mean period of 97 days; six were due to tumor ingrowth and two to biliary sludge. The difference was statistically significant, Roy-Choudbury said.

He speculated that the Luminexx, being cut from a single tube, cannot effectively handle the radial force. He also suggested that the larger interstices in the Luminexx stent allow for more tumor ingrowth than in the Wallstent.

"The Luminexx stent is comparable to the Biliary Wallstent in most aspects apart from primary stent patency, where its performance is significantly worse," Roy-Choudbury said.