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Press Release Date: December 5, 2006
Patients who receive drug-coated stents to open heart arteries may lower their risks of heart attack or death by taking an anti-platelet medication longer than current recommendations, according to a study funded by the Agency for Healthcare Research and Quality (AHRQ) and published today in the online version of JAMA.
The drug, clopidogrel, is an anti-clotting medication currently recommended for 3 to 6 months after placement of "drug-eluting" stents. But the new observational study by AHRQ's DEcIDE Research Center at Duke University suggests the drug reduces risks of heart attack or death for at least 2 years in some patients.
"This study suggests that patients and their physicians should consider extending the period of use of this therapy while monitoring its effects very carefully," said AHRQ Director Carolyn M. Clancy, MD. "Further research will help us understand fully the balance of risks and benefits of extended use of anti-platelet therapy in people who have drug-eluting stents."
Coronary stents are mesh, stainless steel tubes that open blocked arteries. Doctors insert them during angioplasty; after a catheter is guided from the groin to the heart, a tiny balloon inflates the narrowed artery and a stent is left behind to maintain the opening of the artery. Cardiac stents typically measure about three fourths of an inch long and one tenth of an inch in diameter.
Stent placement is a common strategy for patients with heart arteries narrowed by fatty deposits. In 2004, about 542,000 patients were discharged from hospitals after receiving drug-eluting stents. Despite medical advances, heart disease remains the top killer in the United States, claiming about 700,000 lives each year.
The first stents approved in 1994 were bare metal, but stents today are often coated with a thin layer of medication that inhibits the growth of the scar tissue that can cause a repeat blockage. The medication on these "drug-eluting" stents, however, may also slow the healing process that follows stent placement. That is why doctors prescribe clopidogrel, which helps prevent clotting during the extended healing period.
How long clopidogrel may be needed, however, remains uncertain. The drug, which minimizes clotting by stopping blood platelets from sticking together, is currently recommended by the Food and Drug Administration (FDA) for 3 or 6 months for drug-eluting stents, depending on the stent manufacturer.
The Duke study included 4,666 patients who received drug-eluting stents or bare metal stents during a 5-year period. Of those, 3,609 were defined as "event free," meaning they had not died, had heart attacks, or undergone additional procedures to open coronary arteries for at least 6 months since stent placement. Researchers then checked those patients' use of clopidogrel and their health status through September 2006. The study concluded:
- Among drug-eluting stent patients who were event free at 6 months, those who reported clopidogrel use were significantly less likely to die during the next 18 months than those who did not use the drug (a 2 percent death rate vs. a 5.3 percent death rate). These patients were also less likely to either die or have a heart attack (3.1 percent vs. 7.2 percent).
- Among patients who had been event free for a full year, those who reported clopidogrel use at 12 months were similarly less likely than those not taking clopidogrel to die during the next 12 months (0 percent vs. 3.5 percent), and less likely to either die or have a heart attack (0 percent vs. 4.5 percent).
The study also included patients who received bare metal stents. For those patients, the use of clopidogrel did not significantly impact death or heart attack risks in either analysis.
While the Duke study strongly suggests that patients with drug-eluting stents should take clopidogrel longer than current recommendations, a randomized controlled trial is needed to confirm these results, researchers said. In addition, they added, further research is needed to assess the relationship between long-term clopidogrel therapy and its risks for serious adverse effects such as bleeding.
Like any drug, clopidogrel carries risks, and the study did not evaluate the long-term implications of clopidogrel use. A doctor should be consulted before any changes are made in a drug regimen. Clopidogrel can cause excessive tiredness, headaches, dizziness, stomach upset or pain, diarrhea and constipation. Clopidogrel prevents blood from clotting, so patients may experience nosebleeds or prolonged bleeding after an injury.
The FDA, now reviewing its data on drug-eluting stents, will explore safety-related questions at a December 7-8 meeting of the FDA Advisory Panel on Circulatory Systems Devices. Results of the Duke study on clopidogrel will be presented at that meeting.
The Duke study was funded by AHRQ's Effective Health Care (EHC) program. Authorized by the Medicare Prescription Drug, Improvement, and Modernization Act, the EHC program develops unbiased scientific evidence on the effectiveness of medical interventions. The Duke researchers are one of 13 teams nationwide that are part of AHRQ's DEcIDE (Developing Evidence to Inform Decisions about Effectiveness) network, which is part of the EHC. The network conducts new research to help patients, health care providers, and others make decisions about the effectiveness and safety of treatment options. For more information about DEcIDE and the EHC program, go to http://www.effectivehealthcare.ahrq.gov.
For more information, please contact AHRQ Public Affairs: (301) 427-1998 or (301) 427-1855.