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Aspirin is the only over-the-counter
medication that has been proven to help prevent cardiovascular
disease in persons who have suffered a first heart attack
or a transient ischemic attack or who have unstable
angina.
In 1985 U.S. Food and Drug Administration
approved the use of aspirin to prevent heart attacks
in patients who had either suffered a previous heart
attack or suffered from unstable angina. The FDA's decision
was based on a significant body of evidence showing
that aspirin reduced the risk of a second heart attack
by 20 percent. For patients suffering from unstable
angina, the risk of a heart attack decreased by 51 percent.
Aspirin helps reduce the risk of heart
attack by diminishing the clotting action of blood platelets.
A heart attack is known in medical
terms as a myocardial infarction. In a heart attack,
the blood supply to the myocardium (the heart muscle)
is either blocked or severely reduced.
This blockage of the blood supply
to the heart muscle can be caused by either a blood
clot that becomes wedged in a coronary artery or by
the build up of plaque within the arteries themselves.
The length of time that the blood supply is blocked
or severely reduced to the heart muscle may determine
if the heart muscle is significantly weakened or even
suffers cell death.
Aspirin's anti-coagulant ability lessens
the chances of clot formation and reduces the ability
of platelets to block arteries narrowed by accumulated
plaque.
Aspirin may also help reduce the risk
of cardiovascular disease by reducing inflammation in
the blood vessels themselves. The New England Journal
of Medicine reported in April, 1997 that people with
high levels of the inflammation protein marker C-Reactive
were at greater risk of a heart attack. Aspirin reduced
inflammation marker levels and subsequently reduced
the risk of heart attacks by 55 percent. While the research
is still in its early stages, it is theorized that blood
vessel inflammation can lead to hardened and narrow
arteries which precipitates heart attacks.
FDA is currently considering
broadening indications for the use of aspirin.
In June 1996, FDA proposed new rules
that would expand aspirin's professional labeling to
include the use of aspirin during a suspected heart
attack. Studies indicate that one-half of a regular
strength aspirin tablet (162.5 mg) taken at the onset
of a suspected heart attack and continued for 30 days
reduces the risk of death by 23 percent.
The American Heart Association estimates
that 5,000 to 10,000 lives could be saved each year
if people take aspirin when they experience chest pain
or other symptoms of a severe heart attack.
To read the American Heart Association's
scientific statement, "Aspirin as a Therapeutic Agent
in Cardiovascular Disease," please click here.
In January 1997, FDA's Cardiovascular-Renal
and Non-Prescription Drugs advisory committee recommended
that the FDA approve aspirin's preventive role for patient
populations who are at high risk for heart attack and
stroke. Patients who have undergone procedures to restore
blood flow in arteries and veins or demonstrate symptoms
of blocked or narrowed blood vessels, along with sufferers
of stable angina, are included in this high-risk category.
FDA's advisory committee also suggested
that FDA approve the use of a standard low level dose
of aspirin for the prevention of heart attacks and forms
of stroke caused by blockages in blood vessels.
Evidence of aspirin's role in
preventing heart attacks first emerged in 1948. Dr.
Lawrence Craven, a general practitioner in California,
established a small study of 400 men whom he placed
on an aspirin regimen.
Over a two year period, none of the
men suffered from a heart attack. He expanded his initial
study and in 1956 reported that a study of 8,000 men
found that those who took one or two aspirin tablets
daily did not suffer heart attacks.
A 1988 Harvard University study of
22,000 male doctors found that those who took one 325
milligram aspirin tablet every other day had 44 percent
fewer heart attacks than those who did not take aspirin.
The study had been scheduled to last eight years but
the researchers found the results so positive that ethically
they did not feel they should withhold aspirin's benefits
from the control placebo group. (New England Journal
of Medicine; 4/7/88)
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