Shrinking-Stent Flaw to Get Scrutiny for Heart Devices

A complication that causes drug- coated heart stents to weaken and shrink will be reviewed at a medical meeting next week, researchers said.

The stent flaw, known as longitudinal compression, was added to the agenda at the Transcatheter Cardiovascular Therapeutics meeting that starts next week in San Francisco, said Gregg Stone, director of cardiovascular research at New York Presbyterian Hospital/Columbia University Medical Center and director of TCT. Reports surfaced only recently about the issue for the devices that make up a $4 billion market for Boston Scientific Corp. (BSX), Medtronic Inc. (MDT) and Abbott Laboratories.

As manufacturers have made the stents thinner and more flexible, doctors are finding that some products can’t withstand the pressure. The medical journal EuroIntervention published the first case reports with Boston Scientific’s Element, Medtronic’s Endeavor Resolute Integrity and Biosensors International Group Ltd. (BIG)’s BioMatrix earlier this month.

“Stents have a lot of different properties, which vary from one to another,” Stone said in a conference call ahead of the meeting. “Some stents will be more prone to this complication than others. The question is to understand how frequent it is, when does it occur, how to prevent it and how to manage it.”

Researchers who have been investigating the devices will present data on Nov. 7 describing how it occurs, its relevance and the amount of risk stemming from various devices, he said. The TCT meeting runs until Nov. 11.

Market Share Impact

The flaw has the potential to affect market share among Natick, Massachusetts-based Boston Scientific, Minneapolis-based Medtronic and Abbott Laboratories (ABT), based in Abbott Park, Illinois, wrote Larry Biegelsen, an analyst with Wells Fargo Securities in New York in an Oct. 14 note to investors. There is little information available that differentiates the devices from one another, Biegelsen said.

Boston Scientific, which gets about 20 percent of its sales from drug-coated stents, is the most vulnerable, Biegelsen said. Conversations with physicians suggest that Abbott is trying to use the issue “as a marketing advantage” against Boston Scientific’s Element stent, he said.

Boston Scientific’s interim Chief Executive Officer Hank Kucheman said during the company’s third-quarter conference call that the complication is less common than many other problems that stem from clearing clogged arteries. It’s also been linked to numerous devices including Abbott’s Xience stent, while the better visibility of Boston Scientific’s devices make the problem easier to see, not more frequent, he said on Oct. 20.

Restenosis Effect

Longitudinal compression is not a class effect seen in all of the next-generation stents, said Jonathon Hamilton, an Abbott spokesman. It is a function of stent design, which yields varying levels of strength and stability, he said.

The company’s Xience stent has horizontal bars at its connection points, allowing it to withstand pressure, Hamilton said in a telephone interview. The company has had “virtually no reports” of the side effect with Xience, he said.

Medtronic’s latest stent, built on the Integrity platform, uses a new engineering technique that enables it to be formed from a single wire, said spokesman Joe McGrath. The device has “excellent longitudinal strength” because of the design, he said in an e-mailed statement.

The infrequency of events means longitudinal compression isn’t likely to become a major problem for patients, Stone said. Still, it can have significant consequences, including the development of potentially deadly blood clots known as stent thrombosis, he said. It also may be tied to restenosis, when the artery narrows again after treatment, Stone said.

“It’s something we need to be aware about, but it doesn’t seem to be a very common complication,” Stone said. “We have a whole list of reasons for restenosis and stent thrombosis and this one can get added to the list.”

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net