Drug-coated stents are more likely than bare-metal models to cause deadly blood clots in arteries even when patients take blood thinners for 12 months after the devices are implanted, a study found.

Researchers followed patients in Denmark who received Bristol-Myers Squibb’s Plavix blood thinner and aspirin for a year after getting 5,422 drug-coated stents and 11,730 bare- metal devices. There was no difference in clots until the drug regimen ended, when risks rose in those with the coated models, according to the study presented today at a science meeting.

The FDA recommends blood thinners be taken for six months by patients with drug-coated stents made by Boston Scientific and for three months by patients who receive Johnson & Johnson’s coated stents. The agency is considering extending use of the drugs to 12 months for both models sold in the US.

“This calls into question whether 12 months is even long enough,” says William Maisel, a Harvard Medical School cardiologist and chairman of an FDA heart-devices panel

Press release describing the study;
Study abstract;
Bloomberg News story.