I want to digress a little from talking about cholesterol, so that we can talk about the use of aspirin for prevention of heart attacks, strokes, and other blood clotting problems. Aspirin is commonly used for minor aches and pains and to reduce fever.
Aspirin also combats the effects of platelets, blood cells that help blood clot. This helps reduce the number of heart attacks and strokes. Indeed, platelets are essential to human life because an excessively low count would cause bleeding. But platelets can also be involved in too much clot formation. When this occurs, it can block a blood vessel and can lead to many potentially life-threatening problems including heart attack, stroke, and pulmonary embolism (a blood clot in the lungs). It’s important to achieve a balance between too much clotting and not enough clotting.
There is much confusion regarding the use of aspirin in prevention of heart attack and stroke. The use of aspirin to prevent a first heart attack or stroke — called primary prevention — is widely debated. There have been approximately seven clinical trials testing the effects of aspirin in someone with no prior history of heart attack or stroke. The doses have varied from 50mg to 500mg. While not all the trials showed benefit, only one trial showed an increased risk of bleeding, but those were patients on high dose aspirin.
Based on this ambiguous data, the current American College of Cardiology/American Heart Association guidelines recommend aspirin for primary prevention only in men with diabetes and intermediate cardiovascular risk, and without an increased risk of bleeding. Those patients who have a 10% risk of a cardiovascular event over a 10-year period are defined as intermediate risk. The European Society of Cardiology guidelines do not recommend aspirin in primary prevention.
In patients with previous stroke, heart attack, or certain other blood clotting problems, aspirin has beneficial effects. For these people, The American College of Cardiology/American Heart Association guideline recommends starting aspirin 75 mg to 162 mg and continuing indefinitely in all patients unless other medical problems prevent its use. The benefits of aspirin need to outweigh the risk.