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2 Studies Find Drug-Eluting Stents Risky Without Blood Thinner

Heart patients with such stents face higher sudden-death risk, cardiologists report.

TUESDAY, Dec. 5, 2006 (HealthDay News) -- Heart patients with drug-eluting stents implanted to keep their arteries open have a higher risk of sudden death than those getting bare-metal stents if they stop taking the blood-thinning drug Plavix, Swiss and American cardiologists report.

The reports were both released early to coincide with a U.S. Food and Drug Administration advisory panel meeting this week on the safety of drug-eluting stents.

There has been growing concern about the long-term safety of drug-eluting stents, which hold 80 percent or more of the American market. Both studies link the danger of heart attack or sudden death to discontinuation of Plavix (clopidogrel), a drug commonly prescribed for patients who have stents implanted after the artery-opening procedure called angioplasty.

The Swiss study of 746 people who had 1,113 stents implanted did show that the drug-eluting stents did a better job of keeping arteries open. But the incidence of death or heart attack for those patients was 4.9 percent, compared to 1.9 percent for patients with bare-metal stents. The reason was a higher incidence of thrombosis, which is sudden blockage of an artery by a blood clot. The findings were published in the Dec. 19 issue of the Journal of the American College of Cardiology.

The U.S. study of more than 4,600 patients, done by Duke University researchers, found similar results. Patients with drug-eluting stents who stopped taking Plavix had more than twice the risk of death or heart attack than those who continued to take the drug, according to the report in the Dec. 6 issue of the Journal of the American Medical Association.

"The overall risk over the pursuing 18 months was 7.2 percent versus 3.1 percent," said Dr. David F. Kong, assistant professor of medicine at Duke, and a member of the research team. "We also looked at bare-metal stents. The risk of death or heart attack was about 6 percent for those not taking Plavix, 5.5 percent for those taking Plavix.

But the study also showed a marked reduction in the need for repeat angioplasties among patients getting drug-eluting stents -- one in 12, compared to one in five for those getting bare-metal stents.

The immediate issue concerns the use of Plavix for such patients, cardiologists said. "The amount of your benefit hinges on the ability of patients to take clopidogrel long-term," Kong said.

"This [the Swiss] study definitely raises the question of whether these drug-eluting stents should be anti-coagulated for a long period of time," said Dr. John Kao, an assistant professor of medicine at the University of Illinois at Chicago. "What that time period is, is, at this moment, unclear."

Drug-eluting stents now dominate the market, accounting for 80 percent to 90 percent of implants. That situation should continue, said Dr. Robert O. Bonow, director of cardiology at Northwestern University and a spokesman for the American Heart Association, because "they are very effective at preventing restenosis [closure of the artery]."

But in doing so, the drug-eluting stents may also prevent the regrowth of the normal tissue that lines the artery, increasing the risk of thrombosis, Bonow said. Plavix can counter that risk, he said.

"Until we know more, any cardiologist would recommend continued use of clopidogrel," Bonow said. "The uncertainty is how long we keep people on Plavix, indefinitely or for the first two years."

There might be a subset of angioplasty patients for whom bare-metal stents are preferable, Bonow said, such as "patients who have more simple plaques [deposits] in large blood vessels." But drug-eluting stents are preferable in most cases, he added.

Money might enter into the decision as to which stent to use, Kao said. Plavix therapy costs at least $120 a month, he said, and, "at least in my practice, when I evaluate someone who needs intervention, if the patient is on a fixed income and cannot afford to take Plavix for six to 12 months, I put in a bare-metal stent."

Kao's recommendation for Plavix use by people who get drug-eluting stents is "at least a year, indefinitely if they can afford it."

People faced with angioplasty should be aware of "the upside and downside of a drug-eluting stent," Bonow said. "With Plavix, it usually is a risk worth taking."

More information

For more on stents, visit the American Heart Association.

SOURCES: David F. Kong, M.D., assistant professor, medicine, Duke University Medical Center, Durham, N.C.; John Kao, M.D., assistant professor, medicine, University of Illinois, Chicago; Robert O. Bonow, M.D., director, cardiology, Northwestern University, Chicago; Dec. 19, 2006, Journal of the American College of Cardiology; Dec. 6, 2006, Journal of the American Medical Association
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