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The FDA Approves Drug-Eluting Stent for Clogged Heart Arteries
Drug-eluting stents may have a substantial impact on the occurrence of re-blockages for patients with heart disease. Each year 800,000 angioplasty procedures are performed in the United States to open clogged coronary arteries. In approximately 15%-30% of patients, the artery becomes clogged again (a condition called restenosis) within a year, and it must be treated again with a procedure such as angioplasty or bypass surgery.
"Today's approval represents a significant step forward in the treatment of heart disease," said HHS Secretary Tommy Thompson. "Patients who receive this device will need fewer repeat operations to unclog arteries, which can make a real difference in the quality of their lives."
The product is the Cypher Sirolimus-Eluting Coronary Stent (Cypher stent), made by Cordis Corporation, of Miami Lakes, Fla. It is a tiny metal mesh tube that is covered with the drug sirolimus. The company has a license from Wyeth Pharmaceuticals for the use of sirolimus.
The Cypher stent provides a mechanical scaffold to keep the vessel open while the drug is slowly released from the stent to prevent the build-up of new tissue that re-clogs the artery. In studies conducted by the firm, the stent reduced the rate of restenosis by about two-thirds.
"Drug-eluting stents combine drugs with medical devices to provide more effective care for many patients with heart disease," said FDA Commissioner Mark McClellan, M.D., Ph.D. "FDA is working to make sure its regulatory procedures encourage the quick and efficient approval of such safe and effective combination products."
FDA approved the stent based on a review of laboratory and animal tests and two clinical studies of safety and effectiveness conducted by Cordis, as well as review of manufacturing procedures for this new combination product.
In the U.S. study (called the SIRIUS study), 1058 patients received either the Cypher stent or an uncoated stainless steel stent made by Cordis. The patients in the SIRIUS study had blockages of 15mm to 30mm long in arteries that were 2.5mm to 3.5mm wide.
Results were similar for both types of stents in the weeks immediately following the procedure, but after nine months the patients who received the drug-eluting stent had a significantly lower rate of repeat procedures than patients who received the uncoated stent (4.2% versus 16.8%). In addition, patients treated with the drug-eluting stent had a restenosis rate of 8.9%, compared to 36.3% of patients with the uncoated stent. The combined occurrence of repeat angioplasty, bypass surgery, heart attacks and death was 8.8% for drug-eluting stent patients and 21% for the uncoated stent patients.
A smaller study of 238 patients conducted outside of the U.S. (the RAVEL study) was similar to the SIRIUS study, but it evaluated patients with shorter blockage of the coronary artery. That study also showed significant reductions in repeat procedures and restenosis.
This smaller study was the basis for the product's approval in Europe, and supported the product's approval in the United States. While the RAVEL study suggested that the Cypher stent showed promise, it was not large enough to assess the patients most likely to benefit from the device.
The U.S. study evaluated the product's safety and effectiveness in a much broader population. The additional evidence obtained from the U.S. study required by FDA should allow doctors to use the drug-eluting stent with more confidence about the benefits of the product in more patients.
The safety and effectiveness of the Cypher stent in smaller diameter arteries or for longer blockage that required more than two stents was not studied in either trial. Also, the safety and effectiveness have not been studied in patients who are having a heart attack, patients who had previous intravascular radiation treatment, or patients who had their blockage in a bypass graft.
The types of adverse events seen with the drug-eluting stent were similar to those that occurred with the uncoated stent.
Patients who are allergic to sirolimus or to stainless steel should not receive a Cypher stent. Caution is also recommended for people who have had recent cardiac surgery and for women who may be pregnant or who are nursing. Patients who receive the drug-eluting stent will likely need to take certain kinds of anti-platelet drugs for at least several months.
FDA is requiring Cordis to conduct a 2000-patient post-approval study and continue to evaluate patients from ongoing clinical trials to assess the long-term safety and effectiveness of the Cypher stent and to look for rare adverse events that may result from the use of this product.