FDA sounds alarm over drug-eluting stent

Six months after the FDA approved the drug-eluting coronary stent Cypher from Cordis, it has issued a warning that the device causes adverse events, including death.

At least 60 deaths have been linked to the stent because of subacute thrombosis occurring within 30 days of implantation. Another 240 patients who experienced subacute thrombosis required medical or surgical intervention, according to the Oct. 29 FDA report. Nearly 90% of these cases were in the U.S.

Fifty patients experienced hypersensitivity reactions: pain, rash, respiratory alterations, hives, itching, fever, and blood pressure changes. Some of these patients also died.

The Cypher stent is coated with a thin polymer containing the drug sirolimus, an immunosuppressant intended to reduce restenosis. The FDA is unsure about the causes of the adverse events. The agency and Cordis are exploring a number of possibilities including product characteristics, patient characteristics, procedural factors, and a combination of these.

"It is well known that subacute thrombosis is related to implant technique and stent placement," said Dr. Andrew Eisenhauer, director of the interventional cardiovascular medical service at Brigham and Women's Hospital.

Investigations using intravascular ultrasound have found that stents are often poorly deployed or underexpanded. Both of these factors would predispose a patient to subacute thrombosis, whether a stent is bare metal or drug-eluting, Eisenhauer said.

Research suggests that the risk for stent thrombosis may be higher for certain patient types, such as those receiving bifurcational stenting in both the parent and branch vessels. In these cases, the implant technique might need to be modified, he said.

Out of 1000 Cypher implants, Eisenhauer and colleagues have had a few subacute thromboses, a rate not dissimilar to patients receiving bare metal stents, he said.

Cordis has sold about 450,000 stents worldwide, two thirds of them in the U.S.. Hundreds of thousands of patients have been successfully treated with the Cypher. Nevertheless, the FDA warning could make physicians think twice before using the device, said Rochelle Ellis, an analyst with Front Line Strategic Consulting in San Mateo, CA.

Front Line just released a report that predicted sales of drug-eluting stents would triple in the next five years, due mainly to quick acceptance of the product in the U.S. The market for drug-coated stents will grow from $2.1 billion this year to $6.3 billion in 2008, according to the report.

Eisenhauer said it is appropriate for practitioners to reconsider the use of these stents, particularly to assess their implantation technique. Increased use of intravascular ultrasound may help ensure proper deployment.

When drug-eluting stents were finally released, many interventionalists hoped that they would be simple to use and would have antithrombotic as well as antirestenosis properties, according to Eisenhauer.

"I'm not certain that the appropriate care is always taken in their initial implantation," he said.

For more information from the Diagnostic Imaging archives:

• Trials reveal need for changes in drug-eluting stent designs

• Ultrasound noninvasively follows aortic stent-grafts

• Imaging and stenting provide effective therapy

• Interventional radiology stays strong in Sweden