First and Only International Study of its Kind Shakes up Metal Biliary Stent Market


The final results of the largest international, randomized, controlled trial of self-expanding metal stents (SEMS) in the treatment of biliary obstructions reveal a new, disruptive competitive dynamic in the $70-100 million metal stent market. The study, known as MOZART, published in the September issue of Gastrointestinal Endoscopy, found that the overall clinical success of Cook Medical's non-foreshortening nitinol Zilver® Biliary Stent, now available on a 25 percent smaller 6 FR introducer, parallels the effectiveness of Boston Scientific's Wallstent®. The MOZART study confirms that SEMS provide a higher level of patient care and clinical efficacy than alternative solutions.

Landmark Study

The MOZART study included a total of 241 patients in nine centers in the U.S., Canada and Europe who presented with malignant biliary obstructions – a complication associated with several forms of cancers – in which the bile ducts of the liver become blocked by tumors. Biliary obstructions or strictures impair liver function and cause a range of symptoms including abdominal pain, nausea, vomiting, fever and fatigue. The blocked ducts can be opened using stents inserted endoscopically that expand upon deployment. Plastic stents are cheaper than metal for this purpose, but data suggest that plastic stents occlude more readily when compared to SEMS, necessitating repeat procedures. In fact, SEMS have proved more robust and cost-effective in many clinical settings.

aAccording to the MOZART study, the 6-mm SEMS demonstrated a higher occlusion rate than the 10-mm SEMSs; therefore, the study agreed to close this arm to further patient entry and continue to follow the exiting enrolled patients. The remaining 10-mm SEMS patients revealed equal patency among SEMS.

The two biliary stents in the MOZART study differ significantly in design, materials and mechanism of expansion, but achieved equal patency by several measures: for both, fewer than a quarter became occluded after placement over the life of the study. Treating physicians, who had more experience with Boston Scientific's stent, reported the ease of positioning of the Zilver during the study.

“The significance of this study is defined not only by its scope and global reach, but also the noteworthy findings,” said Raj J. Shah, MD, a lead investigator on the study, associate professor of medicine at the University of Colorado Denver School of Medicine and director of pancreaticobiliary endoscopy services at the University of Colorado Hospital. “The Zilver stent has all the advantages of the industry's leading SEMS, including helping us to deliver excellent patient care and expanding cost-effective options for malignant biliary obstruction.”

Cook Medical: The Only Full Line Supplier of Endoscopic Devices

Cook Medical's Zilver Biliary Stent is the first stent of its kind made of flexible laser-cut nitinol tubing. Nitinol, which is inherently kink-resistant, allows Zilver to conform to the ductal wall while providing reliable patency. Through the interlocking design construction, Zilver's stent ends are atraumatic, potentially reducing the risk of ulceration or perforation. Its non-foreshortening design gives precise accuracy in placement; potentially reducing instances of migration and the need for repeat procedures. Additionally, four gold radiopaque markers at each end of the stent provide greater fluoroscopic visualization and exacting placement.

The Zilver Stent is available with the market's smallest introducer platforms (6 and 7 FR), making it ideal for accurate navigation through tighter strictures. Combining the latest in access capability and the proven benefits of Zilver, the 635 is yet another addition to Cook's full line of innovative endoscopic accessories.

Benefits and Offerings of the Zilver 635:


  • Zilver 635 has the markets only 6 FR introducer, the optimal platform for hilar and bifurcation stenting;
  • Utilizes Cook's proprietary Flexor coil-reinforced introducer technology: a truly unique material that has excellent pushability and flexibility while providing a distinct advantage in stent placement due to its kink resistance;
  • The only system in the world that allows two stents to be placed simultaneously through a standard 4.2-mm channel duodendoscope, thereby increasing procedural efficiency;


“The MOZART study results inject a major disruptive element into the SEMS market by unequivocally stating that Zilver performs with a clinical efficacy equal to that of the market leader, but with an introducer 25 percent smaller and on a non-foreshortening nitinol platform,” said Barry Slowey, Business Unit Leader, Endoscopy. “We are pleased to offer Zilver to our customers while delivering the most comprehensive line of endoscopic devices that enhance patient care.”

About Cook Medical

Founded in 1963, Cook Medical pioneered many of the medical devices now commonly used to perform minimally invasive medical procedures throughout the body. Today, the company integrates medical devices, drugs and biologics to enhance patient safety and improve clinical outcomes. Since its inception, Cook has operated as a family-held private corporation. For more information, visit . You may sign up to follow Cook Medical on Twitter at cookmedicalpr.