Why do aspirin work to prevent heart attacks?

Imran K. Niazi, MD
Clinical Cardiac Electrophysiology

Aspirin is an antiplatelet agent. Platelets are tiny blood cells; we can think of them as sacs filled with glue. When there is injury to the wall of an artery, the bags of glue go there and stick together to form a plug. This normal protection against bleeding is harmful when there is cholesterol in the walls of the arteries. Then, the platelets stick to the cholesterol and plug up the vessel. This causes a heart attack.

Aspirin (and similar drugs, like clopidogrel) prevent the platelets from sticking together to form a plug or clot in the heart artery. They have been shown to reduce the risk of heart attack in patients at risk. This includes patients with high blood pressure, high cholesterol or diabetes. Smokers also are at increased risk. Patients who have had stents or bypass surgery also benefit for the same reason.

Intermountain Healthcare
Cholesterol laden plaque in a blood vessel may rupture and this stimulates the body to seal this rupture by laying down platelets which circulate in the blood.  These platelets in turn activate other coagulation factors in the blood and if this goes unchecked a clot forms and a heart attack occurs.  Aspirin acts by inhibiting the platelets from adhering excessively to such a rupture and therefore preventing a heart attack. Cigarette smoking is known to activated platelets and this encourages platelets to clump together. In short this is opposite what aspirin does.
Discovery Health

It turns out that prostaglandins do not just trigger a feeling a pain. They also help blood platelets to clump together to form clots. Aspirin, as it turns out, is an anti-platelet agent. It inhibits the prostaglandin that brings the platelets together. If the clots cannot form in the arteries, the chances of a heart attack dramatically decrease.

Continue Learning about Aspirin

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.