Daily aspirin can help to prevent heart attacks, but the United States Preventive Services Task Force now recommends that:
• adults 60 years and older should not take aspirin to help prevent a first heart attack, and
• those 40-59 years old who are at high risk for heart disease should take aspirin only on their doctor’s recommendation (USPSTF, October 12, 2021).

Taking aspirin daily will reduce clotting, which may help to prevent a heart attack, but it can increase risk for internal bleeding into the brain to cause a stroke or into the stomach to cause bleeding ulcers. The USPSTF message is that people over 60 are more likely to die from bleeding than they are to be protected from suffering a heart attack. However, there is some data to show that daily aspirin may be beneficial in high-risk 40 to 59-year-old people, who are more likely to be protected from a heart attack than they are to be harmed by bleeding into the brain.

If you are already taking aspirin, you should not stop taking it until you have discussed your case with your doctor. Those who have already had a heart attack, stroke, a coronary artery stent, or coronary artery bypass graft surgery may benefit from taking aspirin regularly (JAMA, 2020;323(7):676). Everyone who is at increased risk for a heart attack should talk with their physician and jointly decide if they should take aspirin.

The Data
The USPSTF’s recommendations are based on their review of 13 studies on nearly 165,000 adults, with a mean age of 62 and without heart disease. These studies showed that five years of taking aspirin every day increased nearly the same percentage of major bleeding episodes as it reduced the incidence of heart attacks (JAMA, Jan 22, 2019;321(3):277-287).

Other studies have shown that the number of diabetic lives saved from heart attacks and clotting strokes was offset by the number of diabetics who died from major bleeding into the brain, eyes, stomach, and other places (N Engl J Med, Oct 18, 2018; 379:1529-1539). Diabetes is among the strongest risk factors for suffering heart attacks in North America today with more than 68 percent of Type II diabetics dying from some form of heart disease and 16 percent dying of strokes.

Taking aspirin daily for three years was associated with a reduction in heart attacks in people who had previous heart attacks, but not in those who had not had a previous heart attack (Clin Cardiol, May 2017; Am J Med, 2015 Feb;128(2):137-43). The American Heart Association (AHA) has previously recommended taking daily aspirin only if your chance of developing a heart attack in the next 10 years is greater than five percent (Ann Intern Med, June 21, 2016;164(12):826-35).

Heart Attacks Are Caused By Clotting
Cardiovascular disease is the leading cause of death in the U.S., affecting 600,000 people each year or about one in every three deaths. Heart attacks are not caused by narrowed arteries; they are caused by a plaque breaking off from the inner lining of an artery leading to the heart, followed by bleeding. Then a clot forms that completely obstructs the flow of blood to the heart muscle, and the part of the heart muscle that suddenly has no source of oxygen dies. Aspirin helps to prevent this clotting, but it also increases risk of bleeding into the brain or the stomach.

Risk factors for heart attacks include:
• smoking
• lack of exercise
• high cholesterol
• high blood pressure
• high blood sugar or diabetes
• being overweight
• abdominal obesity
• a pro-inflammatory diet
• family history of heart attacks
• having autoimmune or inflammatory conditions such as psoriasis, HIV, rheumatoid arthritis, lupus or kidney disease, which increase risk for heart disease

Tests that your doctor will use to assess your risk for a heart attack include:
• Blood pressure >120/80
• LDL cholesterol >100
• HDL cholesterol <40
• HBA1c (a test for diabetes) >5.7
• CRP (a marker of inflammation) >1
• Resting heart rate >70
• Triglycerides >150
• Lp(a) (a genetic clotting condition) >130
• Homocysteine >10
Calcium score (CT scan of arteries leading to the heart)

For more information, see:
Heart Attack Prevention
Heart Attack Risk Factors
Stabilizing Plaques with Exercise and Possibly Statins

My Recommendations
I think that using aspirin for occasional pain relief can be safe, but taking aspirin regularly is likely to make you bleed easily, which can harm you and even cause death from a stroke or other internal bleeding. If you are already taking aspirin daily, do not stop without consulting your doctor. He or she will certainly be aware of these new guidelines and you can discuss your individual situation.