Debate on stent safety heats up at conferenceOct 24, 2006 | www.cbsmarketwatch.com
The first day of a major cardiology conference ended with experts unable to agree on whether drug-coated stents are safe enough and should continue to be used over bare-metal devices, a matter that has been haunting the $5 billion to $6 billion global stent market.
Stents are tiny, mesh tubes used to prop open clogged arteries, and drug-coated stents use medication attached by a polymer to prevent tissue growth after implantation.
The drug-coated devices were introduced earlier this decade and quickly became the stent of choice for nearly all stent procedures in the U.S. There is, however, a growing concern that the drug-coated stents may be linked to a slight increase in the risk for dangerous clots months or years after implantation, a condition called late thrombosis.
The cause of the clots isn't certain, and could be linked to polymers, drugs or both. It's theorized that by restraining growth of the vessel around the stent, the device's metal struts are left exposed as a surface on which blood cells can catch.
"If we accept that there is a small increase in stent thrombosis, does it matter? It must matter," said Dr. David Faxon, of Brigham and Women's Hospital in Boston, during a session on the issue at the Transcatheter Cardiovascular Therapeutics conference here. "If late stent thrombosis results in mortality, any level isn't acceptable."
According to Faxon, bare-metal stents, which haven't shown higher risk for the clots, should be used in favor of drug-coated ones in some cases until the issue is better discussed and conclusions are reached.
Although there are other problems associated with the bare-metal devices, none of them are as concerning, Faxon said.
"There is nothing wrong with bare-metal stents," he said, adding that a more common problem associated with those devices, called restenosis, is not as serious a condition. Restenosis, which is the renarrowing of the artery after a stent is put in, can be painful and can lead to complications, including need for more stents.
Faxon said late thrombosis can cause death and because of it, he has decreased the use of drug-coated stents. And he isn't alone, as penetration of those stents in the U.S., which had been about 88% at its peak, has slipped to the 83% to 84% range amid safety concerns.
Dr. Sigmund Silber, of the Cardiology Practice and Hospital in Munich, however, said drug-eluting stents shouldn't be so easily dismissed, as they are highly effective. In addition, he said, the problem of late thrombosis can be dealt with long-term use of anti-clotting medication.
"I'm a little bit surprised that people are surprised (by the thrombosis problem)," Silber said, adding that this was known long ago and can be dealt with by increasing duration of treatment with the anti-clotting medicine.
Both experts, however, agreed that more data and studies are needed so the industry can draw the proper conclusions on the matter. A big problem with the currently available data, they said, is that those conducting studies use different definitions and criteria, which creates results that shouldn't be necessarily compared.
The stent safety issue is likely to continue dominating the Washington conference, which runs until Friday.
Stent makers include Boston Scientific Inc. (BSX), Johnson & Johnson (JNJ), Abbott Laboratories Inc. (ABT), Medtronic Inc. (MDT) and Conor MedSystems Inc. (CONR).