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ATLANTA -- A new weapon in the war on heart disease was approved by the FDA today -- Cordis Corporation's drug-eluting CYPHER stents. Used to prop arteries open following coronary angioplasty, these stents also release the drug sirolimus and have been shown to greatly reduce the risk of restenosis (reclogging of arteries). They are the first U.S.-approved combination drug and stenting device intended to help reduce restenosis of a treated coronary artery.
Angioplasty is the most commonly used procedure in the U.S. to treat potentially life-threatening coronary blockages. During angioplasty, a balloon-tipped catheter is used to push aside atherosclerotic plaques in arteries. Once the vessel has been widened, adequate blood flow is returned and stents (tiny mesh wire tubes) are frequently used to keep arteries open..
However, restenosis has proven to be a frequent problem following angioplasty and stenting. Patients who experience restenosis may require additional angioplasty procedures, another stent or bypass surgery. For many people, the FDA newly approved drug-eluting stents could offer a potential solution to restenosis, which has been called the "Achilles heel" of angioplasty.
The outcome of the Sirius study at the Emory Heart Center and 52 other U.S. medical centers was critical in the FDA's decision to approve the drug-eluting stents. In the randomized, double blind clinical trial involving 1,058 patients, the CYPHER stents were found to greatly reduce restenosis following coronary angioplasty compared to conventional bare metal stents.
"We believe these drug-eluting stents will be a major breakthrough in defeating restenosis after stenting," says Emory interventional cardiologist John S. Douglas M.D., Primary Clinical Investigator for the Sirius study at Emory.
In the Sirius trial, patients received either a plain metal stent or a CYPHER stent coated with the pharmaceutical agent sirolimus. "At eight month angiographic follow-up, patients treated with the CYPHER™stent had an overall 75 percent reduction in restenosis when compared to the control group receiving the bare metal stent," says Emory Heart Center cardiologist Ziyad M. Ghazzal, MD, co-investigator in the Sirius study at Emory.
"In the particular subset of arteries tests, the success rate of the drug-eluting stents was even more dramatic, with a success rate of more than 90% over conventional bare metal stents," says Douglas Morris, MD, Director of the Emory Heart Center. "We are proud that Emory was one of the sites in the U. S. for this extremely important multi-center Sirius study that lead to the FDA approval of the CYPHER stent. I see the drug-eluting stent as a major advance in the treatment of coronary artery disease. It should lead to a profound reduction in restenosis which is the primary deterrent to the even more wide spread applicability of coronary stents."
The sirolimus coating does not kill cells, but allows the endothelium (the layer of cells lining vessel walls and the heart) to cover the stent. "This is important because the stent becomes coated with cells and incorporated into the heart," says Dr. Douglas, who, along with Emory colleagues, implanted the first coronary artery stent in the U.S. at Emory Hospital in l987. Today, three-fourths of all patients undergoing angioplasties receive stents.
He points out that without this cell covering, a stent may promote blood clot formation when the body "reads" the device as foreign material. "In fact, that's one of the limitations of radiation treatment for preventing the renarrowing process in arteries. Radiation prevents the growth of tissue over the stent and that can up the risk for blood clot formation there later and lead to heart attack. The drug-eluting stent appears to be a solution to this problem," notes Dr. Douglas, Director of the Emory Interventional Services.
"We hope the approval of the CYPHER stents will expand the horizon of percutaneous coronary interventions to include more patients that we can help," says Dr. Ghazzal. "If the results of the Sirius trial are reproduced in patients eligible to receive the newly approved drug-eluting stents, the outcome could be the need for far less additional angioplasty and bypass surgery for these people down the line."
Emory has long been in the forefront of advancements in interventional cardiology. In 1977, pioneering cardiologist Andreas Gruentzig, MD, while living in Zurich, Switzerland, invented angioplasty by inserting a catheter into a man's clogged coronary artery and inflating a tiny balloon, which successfully opened the blockage and restored blood flow to the patient's heart. In 1980, Dr. Gruentzig chose to join Emory's faculty to work with other Emory cardiologists, including Dr. Douglas, to vigorously research and refine this intervention.
Following Dr. Gruentzig's death in l985, The Andreas Gruentzig Cardiovascular Center of Emory University was created to continue cutting edge interventional cardiology research and to foster clinical excellence in the practice of interventional cardiology. Gruentzig Center interventional cardiologists have performed over 35,000 coronary angioplasty procedures and today Emory is widely recognized as the international training center for angioplasty.