For decades, American physicians have recommended aspirin to prevent heart attacks, strokes and other vascular events for almost everyone over the age of 40, even those without evidence of a previous heart attack or stroke. Newly released guidelines from the American College of Cardiology and the American Heart Association take a more conservative approach to prescribing aspirin in patients who have not experienced a previous vascular event. That does not necessarily mean you should stop taking your aspirin, and the new recommendations do not apply to people who have already experienced at least one vascular event, like a heart attack, stent or stroke.
The new guidelines are backed by three studies done 2018 (ARRIVE, ASCEND, and ASPREE). Each of these studies found that rates of major internal bleeding were either equal or greater than the number of strokes or heart attacks prevented in patients without a previous vascular event. Since the benefit does not seem to outweigh the risks, the new guidelines recommend only giving aspirin to patients with uncontrolled risk factors and a low risk of bleeding. The guidelines only apply to primary prevention of heart attack and stroke, that is for people who have not already had a stroke, heart attack, stent, or another clot in a vessel. Current guidelines for secondary prevention, preventing a second heart attack or stroke in someone who has already had one, have not changed.
Aspirin interferes with platelet function all over the body. Platelets are the part of our blood that make it sticky. Their job is to make the blood clot. When you cut yourself, platelets cause the blood to stick together to form a clot that keeps you from bleeding too much. Unfortunately, sometimes clots form in places where we do not want them to form, like the vessels of the brain or heart. Clots in those vessels cause strokes and heart attacks.
The most common risk factors for developing a clot in a vessel are hypertension, diabetes, and high cholesterol. The best way to combat the heart attack and stroke risk associated with these factors is to control the disease, with either prescription drugs, lifestyle changes, or a combination of the two. In patients who control their blood pressure, glucose, and cholesterol, the benefits of aspirin do not appear to outweigh the risk of bleeding. In patients with uncontrolled risk factors, aspirin may be beneficial, if bleeding risk is low.
Aspirin does not just affect the platelets in your heart and brain; it also affects the platelets everywhere else. That is why one of the major side effects of aspirin is bleeding. Bleeding in the brain or gut can be deadly. The risks of bleeding are especially high in older adults, those with kidney or liver failure, those with a previous GI bleed or those taking certain medications that also increase the chances of bleeding. The American College of Cardiology recommends that aspirin should never be used for primary prevention of heart attack or stroke in people over 70, regardless of other risk factors, because of the bleeding risk in this age group.
There is clearly a benefit to taking aspirin after you have had a heart attack, stent, or stroke. Studies have found up to a 20% reduction in mortality for people who have had a previous heart attack or stroke just from adding an aspirin. That risk reduction is far greater than the risk of a serious bleed. People should not use these new guidelines as a reason to discontinue aspirin if they have had a previous clot, stent, heart attack, or stroke.
If you have not had a previous heart attack, stroke, or stent and are on an aspirin regimen, you should discuss discontinuing it with your physician if you are concerned about your bleeding risk. In the meantime, the best things you can do for your cardiovascular health and longevity are to eat right, exercise more days of the week than not, quit smoking, and control your blood glucose, high blood pressure, and cholesterol.