Stents are flexible metal scaffolds that prop open vessels after angioplasty to restore blood flow to the heart. Narrowing, or restenosis, of those vessels occurs in roughly 20 percent of patients, forcing doctors to repeat the costly procedure.
However, the new study found stents doped with Taxol are much less likely to fail because the drug retards the growth of cells in the lining of the blood vessels where the stents lie.
The U.S. Food and Drug Administration is now considering the approval of a stent coated with the drug sirolimus, which has also been found to prevent restenosis.
Taxol, or paclitaxel, is commonly used to treat advanced breast and ovarian cancers, as well as certain lung tumors and a form of cancer associated with AIDS. The drug is a synthetic version of a molecule found in the bark of the Pacific yew tree, whose anti-cancer properties were discovered in the early 1960s.
Previous research has found stents that release the drug appear to reduce the rate of restenosis, which typically occurs within the first six months after the procedure. The latest research, reported in the April 17 issue of The New England Journal of Medicine, shows a high dose of the drug works best.
Scientists in the United States, Korea and Hong Kong compared the odds of restenosis in 176 men and women who'd undergone stenting of their coronary arteries. A third received stents carrying a large dose of Taxol and a third had stents with a smaller amount of the drug. The rest received uncoated stents. Patients also were given some form of blood-thinning therapy to reduce their risk of clotting.
After four to six months, those with the high dose of Taxol on their stents showed much less new narrowing than those with dry stents. Patients in the low-dose group also had less restenosis, but the effect wasn't as great.
The study was funded by Cook Inc., a stent maker in Bloomington, Ind. One of the authors also received speaking fees from Boston Scientific, another leading stent maker.
Coated stents cost more to implant, but if they reduce the rate of restenosis they could save money in the long run. Some 850,000 Americans receive stents every year. A recent study found that drug-coated stents cost about $2,000 more than conventional stents, but they managed to recoup much of that difference through eventual savings.
Dr. Lee Giorgi, an interventional cardiologist at the Mid America Heart Institute, part of Saint Luke's Health System in Kansas City, Missouri, says drug-coated stents are "hot stuff."
However, he says, while the data from clinical trials are impressive, it's likely their real-world performance will be somewhat weaker. Not only do trials typically include ideal patients, but the studies take place in heart centers with elite physicians, he says.
"You can almost predict that the results won't be as good" at an average clinic with more difficult patients, he adds.
However, Dr. Kenneth Kent, director of the cardiac catheterization program at Georgetown University Hospital, says heart specialists also had a "learning curve" with conventional stents when they first appeared. Eventually, Kent says, the devices will be as familiar as the old models.
"There's no question that these devices are an answer to a wish ever since we started doing" stenting nearly three decades ago, he adds. Recurrent narrowing of the vessels "has been the single most important deficiency" in the procedure.