Aspirin’s main benefit for heart health is its blood-thinning power, which was first noted in the 1940s. By the late 1970s, doctors were prescribing aspirin to individuals who had suffered heart attacks to help guard against recurrence. But researchers wanted to learn if the medication would help prevent first heart attacks as well.
To find out, the Physician’s Health Study was launched. This clinical trial involved 33,223 male physicians between the ages of 40 and 84 with no history of heart disease. One group received 325 mg of aspirin every other day, while the other group was given a placebo. The study was stopped early on when results clearly showed the benefits of aspirin.
A few years later, the Nurse’s Health Study was launched to learn if aspirin had the same effect in women, which was found to be true. Since then, other studies have confirmed the heart attack and stroke prevention capability of aspirin.
Today, it’s believed to reduce the risk of heart attack in high-risk patients by about one-third. Aspirin works by binding with an enzyme called cyclooxygenase-1 (COX-1) that is involved in the chemical process that causes blood to clot.
Clotting is one of the human body’s most important lifesaving abilities. If you cut your finger and bleed, your blood’s clotting cells, called platelets, build up at the site of the wound. The platelets form a plug that seals the opening in the blood vessel to stop further bleeding.
Such clot-forming action can save your life. But it can also occur inside your coronary arteries, the vessels that supply your heart with blood. People with heart disease have blood vessels that narrowed by atherosclerosis — a buildup of fatty deposits called plaque. Such deposits can also rupture. When that happens, a blood clot can quickly form to seal the rupture. The blood clot blocks the blood from flowing forward and a heart attack can result.
In addition, aspirin is part of a class of drugs called “nonsteroidal anti-inflammatory drugs,” or NSAIDs, which act against inflammation. This is another reason why aspirin may help reduce the risk of heart attack — because inflammation begins the process that results in atherosclerosis.