Aspirin Therapy

Does Daily Aspirin Therapy Prevent Cardiovascular Disease?

By Gordon A. Ewy, MD,
Emeritus Director, University of Arizona
Sarver Heart Center

Almost everyone takes an aspirin now and again for headaches, body aches or fever. It is a rare person who cannot take aspirin because of an allergy. So for the rest of us, the question is who should be taking daily aspirin?

The answer is simple—you should only take daily aspirin on the advice of your physician!

Knowing your medical history, your physician can determine if aspirin-related risks of increased bleeding outweigh the risks of clotting.

Aspirin therapy for the prevention of cardiovascular disease falls into two general categories: Primary prevention is the effort to avoid an initial heart attack or stroke, while secondary prevention is the treatment of patients who have had a heart attack or stroke to deter a recurrence. This article focuses on the role of aspirin in primary prevention— preventing heart attacks and strokes in individuals who do not have heart or vascular disease.

Recognizing Heart Attack Symptoms

Men typically feel pain in their chests
or left arms.

Women’s symptoms are harder to
detect. Most women report weakness,
fatigue, shoulder, stomach or back
pain or shortness of breath.

Cardiac Arrest: No Aspirin Needed

A cardiac arrest often is referred to as “a massive heart attack.” In fact, a cardiac arrest in an adult often is caused by the same thing that causes a heart attack: a blockage of a coronary artery that supplies blood to the heart muscle. The reason the public and the news media often refer to cardiac arrest as massive heart attack is that in the past, very few patients survived. In cardiac arrest, the heart stops pumping blood so the patient with primary cardiac arrest has an unexpected, witnessed (seen or heard) collapse and is not responsive. For a cardiac arrest, the most important steps are: Check! Call! Compress! (Check to see if the person is responsive, Call 911 and Compress—start chest compression- only CPR). This is not an indication for bystanders to give aspirin! (Go to http://heart.arizona.edu/learn-cpr for more details.)

Heart Attack: Aspirin Recommended

Near-continuous blood flow to the heart muscle and the brain is essential for survival. A heart attack—or myocardial (heart muscle) infarction (tissue death due to a lack of blood flow)—usually is caused by a blood clot that blocks a coronary artery that supplies blood to the heart muscle. The blood clot is started by the platelets in the blood stream becoming activated and initiating the blood clot. Aspirin inhibits platelet stickiness, thereby helping to prevent a blood clot. So, if you experience heart-attack symptoms, an aspirin might be helpful.

Stroke: Aspirin Not Recommended

A stroke, a “brain attack,” can be similar to a heart attack in that it can be caused by blockage of the blood supply–an event that might be prevented by aspirin. But unlike heart attacks, a brain attack also can be caused by a rupture of an artery and bleeding into the brain–an event that might be made worse by aspirin! The key is to call 911 and get to the hospital as soon as possible.

Platelet Function

Platelets are an important element of our blood, for if a blood vessel gets cut, the activation of platelets initiates the blood-clotting process— keeping us from excessive bleeding and even death. However if the damage to the vessel is inside an artery, activation of the platelets may initiate a clot that may block the artery. Abnormal or excessive clotting is a major cause of cardiovascular disease.

How Does Aspirin Work?

Aspirin interferes with normal platelet function. For primary prevention, the major use of aspirin is for antiplatelet therapy: to prevent platelets from sticking together and initiating blood clotting. But aspirin therapy also increases the risk of bleeding. If you have had a heart attack or stroke due to a blood clot, your doctor will likely recommend that you take a daily aspirin. If you are a middleaged person with diabetes or an older person with cardiovascular risk factors, you are at increased risk for intravascular clotting and chronic aspirin therapy may be indicated.

What is the data for or against daily aspirin therapy?

A recent analysis of nine randomized controlled trials of aspirin therapy versus placebo (followed for at least six years) involving more than 100,000 participants, found that aspirin treatment reduced total cardiovascular disease events (but mainly nonfatal heart attacks) by 10 percent. The number of patients needed to be treated for six years to prevent one cardiovascular disease event was 120. There was no significant reduction in cardiovascular death. However, there was an increased risk of significant bleeding events; the number of patients needed to be treated to cause harm was 73. (Seshasai et al. Arch Intern Med 2012;172:209).

This means that if you treat 100 apparently healthy individuals with aspirin, you are more likely to cause harm than good.

Bottom line: you only should take daily aspirin on the advice of your physician!

For more health information, please visit our Heart Health page.
For physician appointment information, please call 520-MyHeart (694-3278).

If this information is useful to you, please consider a donation to support University of Arizona Sarver Heart Center's research and education mission.