In Cold Blood
An expert panel considers a chilling possibility: The most popular type of stent may be unduly risky
Back to basics. One of those alternatives, says cardiologist Robert Califf, director of the Duke Translational Medicine Institute in Durham, N.C., is a return to basics. "Bare-metal stents aren't used often enough," he says. Newer versions, such as the Driver from Medtronic and Vision from Abbott Laboratories, are made from cobalt-chromium wire rather than the usual stainless steel. The stronger material allows thinner wires. That seems to cause less injury to the artery wall, which in turn apparently lowers the incidence of rampant tissue regrowth.
Meanwhile, however, some 80,000 people a month are joining the coated-stent ranks. The FDA, manufacturers, and physicians all desperately want them to take their prescribed clopidogrel. But the drug, which has no good alternative, costs $3 to $4 per daily tablet. Easy bruising is fairly common. And while the drug's antiplatelet ability lowers thrombosis risk, it raises the risk of excessive bleeding. Kenneth Kent, a Washington, D.C., cardiologist who helped test the first bare-metal stents in the late 1980s, recalls a patient who, for fear that his stent would clot, talked his gastroenterologist into letting him stay on clopidogrel prior to a colonoscopy rather than discontinuing it the usual five days beforehand. The doctor snipped out a small polyp for biopsy during the procedure; the patient bled profusely and had to be hospitalized.
While Kent believes that any added risk from coated stents is very small, he and his colleagues at the Washington Hospital Center have cautiously dropped the percentage of coated stents they implant from the high 80s to the low 60s over the past few months and are likely to drop it further. "There really should be a good reason for using these devices," he says–such as in a small vessel, which is more likely to reblock if a bare-metal stent is employed.
"I try to push off any elective procedure for at least a year after putting in a coated stent," says Phillip Horwitz, an interventional cardiologist at the University of Iowa Hospitals and Clinics in Iowa City. The possibility of future surgery pushes some cardiologists entirely into the bare-metal camp.
Both camps will get the chance to state their case this week. Indications are that, at a minimum, the panel will recommend stronger FDA language about selecting patients suitable for coated stents and extending the aspirin-plus-clopidogrel regimen to a year. Those present are likely to witness sharp questioning by panel members of manufacturers and physicians who use coated stents on their patients. The stakes, in lives and dollars, are high.
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