Do drug-eluting stents carry thrombosis risk?

November 20, 2006

Drug-eluting stents (DESs) greatly reduce the chances of restenosis, a gradual growth of abnormal cells within the stent. However, the results of a new study reveal that DESs may also put patients at a higher risk for a sudden and potentially fatal thrombosis.

Drug-eluting stents (DESs) greatly reduce the chances of restenosis, a gradual growth of abnormal cells within the stent. However, the results of a new study reveal that DESs may also put patients at a higher risk for a sudden and potentially fatal thrombosis.

Data from the BASKET-LATE trial showed a more than threefold increase in death or myocardial infarction (MI) with DESs in the year after clopidogrel (Plavix, Sanofi-Aventis/Bristol-Myers Squibb) discontinuation. Clopidogrel along with aspirin is usually prescribed for the first six months to a year following stent placement. The new data suggest that the current antiplatelet regimen may not be long enough to provide adequate protection from late thrombosis with DESs.

So it's kind of a double-edged sword, said David Brown, M.D., chief of cardiology at Stony Brook University Hospital, in New York. "The good news is the drugs prevent the in-growth of smooth muscle cells; the bad news is they may also prevent the in-growth of endothelial cells, which are what you need to reduce the thrombotic risk," he said.

For patients who have a DES and have concerns about the risk of prolonged use of clopidogrel, a drug that is associated with bleeding, physicians and pharmacists have to walk a thin line. "There are competing risks that have to be evaluated with Plavix, such as risk of bleeding," said Steven Nissen, M.D., chairman of the department of cardiovascular medicine at the Cleveland Clinic.

So how concerned should patients with a DES be about the risk of late thrombosis? "The numbers are very low," said Madhu Natarajan, M.D., an interventionist cardiologist at McMaster University in Hamilton, Ontario. "If this were a real problem-with the numbers of patients who are getting stents in North America and Europe and the complexity of cases-we should actually see this much more often."

So what's the take-home message for healthcare practitioners as well as patients regarding late stent thrombosis? "Reevaluate the Plavix regimen," said Brown, who also asserted that in real-world practice, the numbers for late thrombosis in patients with DESs are "very small."

For their part, major stent manufacturers are not going quietly into the night. Cordis Corp., a division of Johnson & Johnson, which makes the Cypher stent, released the results of an independent study conducted by the Harvard Clinical Research Institute that shows the Cypher DES is not associated with an increased overall risk of thrombosis compared with bare-metal stents. Cordis has also expanded a registry that will evaluate safety and efficacy measures, major adverse cardiac events such as heart attack and death, in-stent thrombosis, and information regarding the use of dual antiplatelet therapy.