The heart of a stent debate

People With Drug Coated Stents Are Propane To Fatal Blood clots. Michael Young had a choice.
Doctors could clear his three blocked coronary arteries by cracking open his chest and surgically bypassing them. Or they could clear them from within by inflating a tiny balloon and propping them open with wire-mesh stents, coated with a drug to keep the arteries from closing again.

But drug-coated stents can be risky, too. New studies show that people with drug-coated stents who stop taking their anti-clotting medication now recommended for just three to six months are prone to rare but potentially fatal blood clots for years.

Young, 62, was aware of the risks, but when his surgeon told him that the less-traumatic procedure would be “adequate,” he decided that it was the way to go.

“I decided to put myself in the hands of my doctors,” says Young, a real estate broker from Providence. He had two of his arteries treated Nov. 16. He’s due to have the third fixed soon.

But even doctors are divided about the safety of the tiny devices now implanted in about 6 million people worldwide. The debate is so contentious, and doctors are so uncertain what to do, that the Food and Drug Administration will convene a panel of experts for a two-day meeting Thursday and Friday in Gaithersburg, Md., to determine whether the agency should revise its guidelines for the $6 billion-a-year stent market.

“The FDA is doing the absolute right thing,” says cardiologist and stent expert Judith Hochman of New York University School of Medicine.

Mixed signals

The market has exploded in the past two decades, says Donald Baim, chief medical officer of stent manufacturer Boston Scientific. Today, about 1 million people a year have angioplasty, compared with 300,000 who have bypass operations. About 600,000 angioplasty patients receive stents, doctors say.

“We have a technology that has really changed the way medicine is practiced,” says Daniel Schultz, director of the FDA’s Center for Devices and Radiological Health. “We’re also getting signals that there is, in fact, a risk that may be higher than we had seen in the initial clinical trials.”

The problem is new and the studies are difficult to interpret, so doctors aren’t sure how widespread it is.

An analysis by Deepak Bhatt of Cleveland Clinic published last week in the American Journal of Medicine suggests that the risk of developing a blood clot may be up to five times higher for patients with drug-coated stents than for those with bare-metal stents. A study released in October by Gregg Stone and Martin Leon of the Cardiovascular Research Foundation pegged the risk at about 0.5% a year — or five for every 1,000 drug-coated stent patients.

“There’s continuing uncertainty as to what the true risk really is,” says Robert Bonow, chief of cardiology at Northwestern University.

To reduce the risk of clots, the FDA recommends that patients stay on anti-clotting medicines, aspirin and clopidogrel (sold as Plavix), for three to six months after the stents are put in. Most blood clots appear months to years after the stents are in place, suggesting that patients should take the two medicines much longer.

As a precaution, some doctors, including Bonow and David Williams of Rhode Island Hospital, recommend patients take Plavix for a much longer period. But not everyone agrees. Although Plavix, the second-leading seller of all drugs in the USA, has been shown to be relatively safe, it can cause bleeding, especially in patients who have ulcers or have surgery, Stone says, and it’s also costly.

“You’ve got 6 million patients worldwide, and the drug costs about $4 a day. That’s about $24 million a day,” he says. “On top of that, every year you’re treating another million or so patients. It’s not impossible to spend that kind of money, but we have to know that it’s safe and it works. Right now we don’t.”

But the risks of not taking Plavix long-term may be higher, a study in today’s Journal of the American Medical Association reports. In the study of more than 4,600 patients, researchers found that those who stopped taking Plavix from six months to a year after their drug-coated stents were put in place were more than twice as likely to die or have a heart attack than those who stayed on their medication.

“One of the striking things about our study is that we didn’t see any point at which the risk diminished,” says lead author Robert Califf of Duke University.

Drug-Coated Stents Were Developed to Counter A Side Effect

‘Two sides to every story’

The irony is that drug-coated stents were developed to counter a side effect commonly seen with bare-metal stents: the regrowth of tissue within the artery that shuts it down again. Patients may find themselves experiencing the same symptoms that led to angioplasty in the first place. Some may need a repeat angioplasty or a bypass operation.

For the most part, some doctors argue, the symptoms of tissue regrowth are relatively benign, while a blood clot can cause a heart attack. “We’re talking about significant heart damage that can be fatal,” says Williams, who performed Young’s angioplasty.

But there’s disagreement here, too. Stone asserts that new studies suggest that, in 3% to 19% of cases, re-clogged arteries make themselves known by causing a heart attack. He argues that the risk of a blood clot and the risk of re-narrowing balance out. “As in everything in life,” he says, “there are two sides to every story.”

Hence FDA’s decision to hold an advisory committee meeting. “We want to get all of the data that’s currently available on the table in a neutral setting, where there isn’t a bias one way or another.”

The agency’s recommendations, he says, “will depend on the level of consensus and where the discussion ends up taking us.”

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