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Senior Citizen Health & Medicine
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Drug Eluting Stents
These
stents are coated with a drug that helps prevent recurrent
blockage from forming inside the metal. With the advent of this
new technology, only around five percent of patients receiving
angioplasties and stent placements will suffer a recurrent
blockage in the treated artery. –
Southeast Houston Cardiology |
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Death Risk Lowered for Patients Getting Drug-Eluting
Stents by Longer Use of Anti-Clotting Drug
Medication on
'drug-eluting' stents may slow the healing process
December 6, 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 and published December 5 in the online
version of JAMA. (See FDA statement below news report.)
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.
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About
Clopidogrel |
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Clopidogrel is
used to prevent strokes and heart attacks in patients at risk
for these problems. It works by helping to prevent harmful blood
clots. It is in a class of medications called anti-platelet
drugs. Clopidogrel is also sometimes used to prevent blood clots
in patients with mitral valve disease and patients undergoing
certain heart procedures. - MedLinePLUS |
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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 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
www.effectivehealthcare.ahrq.gov.
FDA Statement on Coronary Drug-Eluting Stents
FDA is providing the following information in
response to inquiries asking for the agency’s position on adverse events
related to coronary drug-eluting stents (DES). This information
describes our position at this time and does not represent new agency
policy. Updated September 14, 2006
FDA has been closely monitoring DES since they
came to the United States market in 2003 and 2004 – and will continue to
do so.
We are aware of recent data suggesting a small but
significant increase in the rate of death and myocardial infarction
(heart attack) possibly due to stent thrombosis (a blood clot in the
stent) in patients treated with DES. The specific studies that have
prompted recent media inquiries are the BASKET-LATE study (presented at
the March 2006 American College of Cardiology Scientific Sessions in
Atlanta, Ga.) and more recently, the Camenzind meta-analysis (presented
at the September 2006 European Society of Cardiology Annual
Meeting/World Congress of Cardiology Meeting in Barcelona, Spain). The
small but significant increase in the rate of death and myocardial
infarction observed in these studies was noted in patients followed 18
months to 3 years after stent implantation.
While the studies presented at the Atlanta and
Barcelona meetings have raised important questions, the data we
currently have do not allow us to fully characterize the mechanism,
risks, and incidence of DES thrombosis. A more formal evaluation of the
data in these studies is necessary, and any conclusions are dependent
upon a thorough peer review. FDA intends to more formally evaluate the
studies presented in Atlanta and Barcelona.
Stent thrombosis in patients who receive DES is a
primary area of interest for the agency because of the potential for
serious adverse outcomes—even though stent thrombosis occurs at low
rates. Over the past two months, the agency has met with both
manufacturers of the FDA-approved approved DES to discuss any
information and perspectives they have that may be pertinent to this
issue. In assessing the risk of stent thrombosis, we remain keenly
interested in the long-term follow-up of patients enrolled in the
original pivotal DES randomized trials as well as those in the more
complex patient and lesion subsets (for example, patients with diabetes;
acute myocardial infarction or multiple vessel disease; or lesions
involving arterial bifurcations, the left main coronary artery, and long
arterial segments) who are currently being treated in “real
world” randomized and registry studies.
FDA also continues to closely evaluate information
related to the duration of treatment with clopidogrel (Plavix), a drug
used in combination with aspirin to reduce/prevent clotting in DES
patients. Although the duration of clopidogrel appeared to be adequate
for the selected patients in the original clinical trials conducted to
support FDA approval, the agency recognizes that the optimal duration of
clopidogrel in more complex patients has not been defined. The
recommended duration of clopidogrel administration and patient
compliance with the prescribed regimen are likely interrelated with
patient and anatomical factors that are associated with DES
thrombosis. Additional clinical data are likely needed to reach
conclusions regarding the optimal antiplatelet therapy regimen for DES
patients.
FDA will convene a public meeting of the
Circulatory System Devices Advisory Panel by the end of the year in an
effort to improve our knowledge regarding the incidence and timing of
stent thrombosis as well as the appropriate duration of clopidogrel use
in patients who receive DES. This Panel of outside experts will assist
the agency in the review and analysis of the available scientific data
and provide recommendations for appropriate actions to address this
issue, such as possible changes to device labeling or the need for
additional clinical studies. An announcement of this meeting will appear
on FDA’s web site,
www.fda.gov/cdrh.
At this time, FDA believes that coronary DES remain
safe and effective when used in patients having clinical and coronary
anatomic features similar to those treated in the pivotal trials
conducted by the manufacturers for FDA approval. The approved
indications are:
The CYPHER Sirolimus-eluting Coronary Stent is
indicated for improving coronary luminal diameter in patients with
symptomatic ischemic disease due to discrete de novo lesions of length ≤
30 mm in native coronary arteries with reference vessel diameter of ≥2.5
mm to ≤3.5 mm.
The TAXUS Express Paclitaxel-Eluting Coronary Stent
System is indicated for improving luminal diameter for the treatment of
de novo lesions ≤28 mm in length in native coronary arteries ≥2.5 to
≤3.75 mm in diameter.
For more information, see
http://www.fda.gov/cdrh/pdf2/P020026.html and
http://www.fda.gov/cdrh/pdf3/P030025.html.
For thousands of patients each year, these devices
have resulted in a significant reduction in the need of second
procedures to treat restenosis. The FDA will continue to carefully
evaluate all DES data in an attempt to maximize the benefits and
minimize the risks for patients undergoing this therapy for treatment of
their coronary artery disease.
To summarize:
● FDA has been monitoring coronary drug-eluting
stents closely since they came on the U.S. market in 2003 and 2004, and
will continue to do so.
● New data were released recently that suggest a
small but significant increased risk of stent thrombosis in patients who
have drug-eluting stents. The agency is keenly interested in this issue
because of the potential for serious harm to patients—even though stent
thrombosis occurs at low rates.
● While the new data are of interest to FDA and
raise important questions, we do not have enough information yet to draw
conclusions. It’s unclear, for example, what causes drug-eluting stent
thrombosis, how often it occurs, under what circumstances it occurs, or
what the risk of occurrence is in a given patient.
● To better understand this issue, FDA met with
the two manufacturers of these products in recent months to discuss any
information they might have pertaining to this issue and get their
perspective. In addition, we plan to convene a public panel meeting of
outside scientific experts in the near future to assist us in a thorough
review of all the data and make recommendations about what actions may
be appropriate, such as possible labeling changes or additional studies.
At this time, FDA believes that coronary
drug-eluting stents remain safe and effective when used for the
FDA-approved indications. These devices have significantly reduced the
need for a second surgery to treat restenosis for thousands of patients
each year.
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