Most patients with drug-coated stents face an increased risk of heart attacks and death, but it's unclear whether their already poor health or the devices are to blame, federal health advisers said Friday.
The advisers found that all stent users had an increased risk of blood clots. And there are more severe risks among the 60 percent who have more complicated health issues.
Those patients have arteries that are narrower or more damaged, or they receive overlapping or multiple stents in a single blood vessel - cases not originally studied before the devices received FDA approval.
Still, the panel of experts split on the strength of the evidence concerning so-called off-label use.
"We feel that there are significant uncertainties and it is difficult to make conclusive judgments regarding this issue," said panel chairman Dr. William Maisel, of Beth Israel Deaconess Medical Center in Boston.
Panelists recommended stent patients take blood-thinning drugs for at least a year. They also said the labels on the devices should be updated to warn doctors that off-label use won't give the same results as seen in generally simpler cases involving healthier patients.
A day earlier, the same panel concluded that the drug-coated stents are safe when used as directed but may put patients at risk for blood clots. Use as directed involves healthier patients with less complex problems. They account for only 40 percent of cases.
"If these stents are really doing what they're supposed to do, please help alleviate the fear that many of us are experiencing," stent patient Rick Dulin, 51, told the panel Friday. The Rockville, Md., resident urged the medical establishment to provide stent patients with more support and more current information.
The stents combine a tiny mesh tube, used like scaffolding to prop open arteries, and a drug coating. The drugs elute, or dissolve, into the body to prevent reclogging of arteries that can require follow-up surgery. That's their advantage over the plain, bare-metal stents.
The FDA is concerned by a small but significant increased risk of clotting associated with the combination stents. The agency convened the outside panel of experts to examine the issue and provide recommendations.
Dr. Steve Nissen of the Cleveland Clinic suggested strengthening the language on the devices' labels to reflect the uncertainty of their safety in broader populations.
"I want to warn people a little more than we do now," Nissen said.
But the lack of evidence from studies left some panelists unable to make a strong recommendation.
"I haven't heard anything today that's going to change my practice when I go back Monday morning," said Dr. Christopher White, of the Ochsner Clinic in New Orleans.
Some suggested any evidence of increased risk compared to on-label use is muddied by the health of the patients.
"The differences, if there are any, are likely to be confounded by differences in the patient population," said panel member Dr. Warren Laskey, of the University of New Mexico's medical school.
The two companies with US approval to sell the stents, Boston Scientific Corp. and Johnson & Johnson, said there is no increased risk in off-label patients or, if there is, that it's probably attributable to their health status.
The panelists also told the FDA that companies seeking to bring new drug-coated stents to market should carry out longer and larger trials in humans to understand the clotting risk. Both Medtronic Inc. and Abbott Laboratories hope to enter the more than $5 billion US market for the drug-coated stents.