Longitudinal Compression in Drug-Eluting Stents on the Agenda

Bloomberg.com reports on a complication that causes drug-eluting coronary stents to weaken and shrink, which will be reviewed at the Transcatheter Cardiovascular Therapeutics meeting in San Francisco next week, according to researchers.

According to Bloomberg;

This potential stent flaw was added to the agenda at the Transcatheter Cardiovascular Therapeutics(TCT) meeting that starts next week in San Francisco, according to 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.

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 firstcase 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.

Potential Problems

“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.”

Medlatest adds that the original paper which has apparently sparked the concern does not itself ring any dramatic alarm bells, but does suggest that “whilst thinner struts and a lower metal:artery ratio aid stent delivery, the downside is to reduce radial strength.”

It seems to be accepted that; “mechanical engineering is a science of compromise.  Altering any one feature of a stent platform will modify other aspects of how a stent performs.”

Source: Bloomberg.com, Eurointervention, Transcatheter Cardiovascular Therapeutics, medlatest staff