WEDNESDAY, Jan. 14, 2004 (HealthDayNews) -- Stents coated with a cancer drug sharply reduce the risk that the vessels they widen will narrow again, but only if the drug is released slowly and carefully, a new study suggests.
Stents are metal scaffolds that prop open narrowed blood vessels and restore healthy blood flow to the heart. Coating stents with drugs is all the rage among cardiologists, and advocates of the technology claim it prevents re-narrowing and chest symptoms. They argue that while coated stents cost much more than conventional devices, they pay for themselves in the long run by reducing the need for additional procedures to reopen vessels.
Just how much of a difference drug-coated stents make, however, isn't clear.
Researchers reported last spring that stents coated with paclitaxel reduced return narrowing better than stents without the drug. But that study was small, only 176 patients, and a larger trial failed to confirm the effect.
One explanation, scientists reasoned, was the drug was coming off the stents too haphazardly, without adequate timing or dosing. Modifying the stent with a plastic matrix that slows the release of the drug might improve its ability to prevent narrowing, they thought.
In the new study, the largest yet to test a drug-coated stent, researchers pitted a new stent with slow-release paclitaxel -- the active ingredient in the breast and ovarian cancer drug Taxol -- against a bare metal model in 1,314 men and women with coronary artery disease. After nine months, 732 patients had an X-ray video scan -- called angiography -- of their stented artery to see how well the device was functioning.
At the nine-month mark, the advantage of the drug-coated stents was clear. Only 7.9 percent of the people who received them had narrowing in the treated vessel, compared with 26.6 percent in the group that got the uncoated stent -- a 70 percent reduction.
Patients with coated stents had about a quarter the rate of additional procedures to open their ailing vessels, 3 percent versus 11.3 percent. They also were about 60 percent less likely to have significantly reduced blood flow in the treated artery.
"We found there was a very profound and robust reduction" in return narrowing, or restenosis, says study leader Dr. Gregg Stone, a heart specialist with the Cardiovascular Research Foundation in New York City.
Rates of heart attacks and deaths were similar in the two groups of patients. But that's not surprising, says Stone, whose group reports the findings in the Jan. 15 issue of the New England Journal of Medicine. "We don't expect a drug-eluting stent to reduce death or [heart attacks]. All we expect it to do is to reduce scar tissue growth at the site of the stent," he explains.
The new stent is being developed by Boston Scientific Corp., a leading stent maker. It has yet to be approved for use in the United States, says Stone, who has been a paid consultant for the company.
Despite their great promise, drug-coated stents aren't without problems. The U.S. Food and Drug Administration recently said it had received reports of more than 360 clotting cases and 70 deaths associated with the device, made by Cordis Corp., a division of Johnson & Johnson. However, experts stress the clots were no more likely in drug-coated stents than in normal ones, and that many thousands of other patients had no problems.
The Cordis stents are coated with the antibiotic sirolimus, which is intended to decrease inflammation and scarring around the scaffolding and prevent re-blockage of the artery.
The latest study did not see a high rate of clots in patients who received those drug-coated stents, the researchers say.
Dr. Thomas Lee, a cardiologist at Harvard Medical School in Boston and author of an editorial accompanying the journal article, says heart specialists have "some worry" about the clotting potentially tied to drug-coated stents. But, he adds, "I don't really see that there's any reason to believe they're more dangerous than regular stents."
A bigger fear, adds Lee, who is also medical director for Partners Community HealthCare Inc., a health system affiliated with Harvard hospitals, is that doctors will rush to embrace the new stents. "I worry that people will throw them around and overuse them" because of the hype that attends the devices.
More information
To learn more about angioplasty and stenting, visit the CardiologyChannel or HeartCenterOnline.
