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Study puts stents on their mettle

By Tina Ting-Lan Chang

Stent" may not be quite a household word, but more than a million of the tiny mesh tubes are used annually in the United States. Stenting—the insertion of one of the little tubes in a blocked blood vessel, to prop it open—has become a common way to treat a variety of coronary diseases. But for the past five years, ever since the development of a new kind of stent, there's been debate over whether the old kind or the new kind is better. A recent study from Dartmouth has brought some solid data to bear on the matter.

Vessel: A major problem associated with stenting is restenosis—the reblockage of the stented vessel. Restenosis occurs because the body sees the stent as a foreign object and initiates a healing response, which results in a buildup of smooth muscle cells around the stent. This narrows the vessel again and often requires the insertion of another stent—a process known as subsequent revascularization.

So scientists developed drugs that prevent the proliferation of smooth muscle cells. Since 2003, there has been a

The bottom line, says Malenka, is that . . .
"nothing is risk-free."

choice between using a stent coated with these drugs—known as a drug-eluting stent (DES)—or an older, bare-metal stent (BMS). After DESs were shown to reduce the rate of restenosis by 50%, their use took off. About 60% of patients were receiving them within a matter of months.

"That's revolutionary," says Dartmouth cardiologist David Malenka, M.D., of how fast the new technology was adopted. He led the recent study, which compared DESs to BMSs. It was prompted by the fact that although DESs reduce restenosis, patients with a DES had an increased rate of blood clots in the stent—a phenomenon known as stent thrombosis. Were BMSs perhaps better after all?

Claims: To answer that question, Malenka looked at Medicare claims data for patients with coronary stents—38,917 who got BMSs before the introduction of the DES, and 28,086 from the post-DES

era; more than 61% of the latter got a DES. The finding—published in the Journal of the American Medical Association—was that post-DES patients had a lower incidence of subsequent interventions. The authors concluded that DESs' "decreased rate of restenosis and subsequent revascularization, with their attendant risks, could more than compensate for a small increased risk of stent thrombosis from drug-eluting stents."

But even though the study—which was funded by the National Institute on Aging and the Robert Wood Johnson Foundation—showed a net benefit from DESs, Malenka says "we still need to learn more about how to minimize the risk of late stent thrombosis."

To do that, patients can stay on anticlotting drugs longer, use a BMS instead of a DES, or choose an alternative treatment. The bottom line, says Malenka, is that patients and physicians should weigh patient-specific risks and benefits. "Nothing is risk-free," he notes. "People have options; people have choices."

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