Drug-Coated Stents Safe, Study Concludes
Thursday, January 24, 2008
Doctors can safely use drug-coated stents to open up complicated blockages in coronary arteries for which the devices were not originally designed, according to new research. In fact, they appear to work better than older, bare-metal stents in those situations.
About half of stents currently placed in heart patients in the United States are used "off-label" -- for purposes not officially approved by the Food and Drug Administration.
"In off-label use . . . there is no mortality increase, and they are more effective than bare-metal stents in sicker, higher-risk patients," said Oscar C. Marroquin of the University of Pittsburgh, who headed a study published in today's New England Journal of Medicine.
Earlier studies suggested that when drug-secreting stents are used off-label, the patient runs an increased risk of clotting and heart attacks. In late 2006, an expert panel convened by the FDA concluded that the risk was small but that it warranted further examination.
Although stent placement remained extremely popular -- about 6 million of the devices have been implanted worldwide -- the use of drug-secreting devices fell from 80 percent to about 60 percent.
Stents are short tubes made of wire mesh and are used to treat people with narrowings in the coronary arteries, which deliver blood and oxygen to the heart muscle. Inadequate blood flow through a coronary artery or one of its branches can cause chest pain; a complete blockage can cause a heart attack.
As an alternative to bypass surgery, cardiologists snake a long catheter into the arteries from a vessel in the leg or arm. The doctors then inflate a small balloon to widen the narrowed section and release a spring-loaded stent to keep it open.
About 15 percent of stented arteries become dangerously narrow again in the months after the procedure because of scar tissue caused by irritation associated with the stent.
Coating the stent's metal with an anti-inflammatory drug slows the growth of scar tissue and can reduce the rate of re-narrowing by two-thirds, to about 5 percent.
The coated stents cost about $2,400, compared with $800 for their bare-metal counterparts.
The "drug-eluting" devices are approved only for placement in straight, short segments of the arteries, but they are widely used in trickier areas -- such as where arteries branch, or in grafts from previous bypass surgery -- a practice that is legal.
In the new study, researchers looked at the experiences of 6,551 people who received bare-metal or drug-secreting stents at more than a dozen hospitals in the United States. Both types were used off-label about half the time.
The study found that even though re-narrowing occurred more often in off-label uses than in approved ones (13 percent vs. 8 percent), the drug-secreting stents reduced the rate by about one-third, compared with bare-metal stents, in the year after the device was inserted. Furthermore, patients who received a drug-coated stent in an off-label area had about the same chance of dying or having a heart attack as patients who received a bare-metal stent in the same place.
There is a small chance -- about 1 in 250 -- of a clot forming in a stent and blocking the artery, a complication that can cause a heart attack and even death.
Theoretically, that may be more likely to occur with a drug-coated stent because the drug can inhibit a protective layer of cells from growing over the wire mesh, but this study suggests that that problem is not more likely to happen over a course of a year than it would with a bare-metal stent.
In a second study published in the New England Journal of Medicine, researchers at the State University of New York at Albany compared bypass surgery with stent placement for people with coronary artery disease. The outcomes were virtually identical.
Of the patients with three blocked arteries, 94 percent who had surgery and 93 percent who received stents were alive a year and a half after their procedures. For those with two blocked vessels, the survival rate was 96 percent and 95 percent, respectively.