I take low-dose aspirin to prevent a heart attack. Do I need to worry about bleeding risks?

DEAR DOCTOR K:

I had a heart attack several years ago. I have been taking low-dose aspirin ever since to prevent a second one. Do I need to worry about bleeding risks?

DEAR READER:

Every medicine contains risks as well as benefits. The question with any medicine is: Do the benefits outweigh the risks?

Aspirin helps prevent repeat heart attacks in two ways. A heart attack occurs when the flow of blood through one of the heart’s arteries is blocked. Without a blood supply, the part of the heart that gets its blood from that artery dies. Most such sudden blockages begin when a cholesterol-filled plaque of atherosclerosis ruptures. Plaques rupture when there is inflammation inside them.

When a plaque ruptures, it spills cholesterol into the blood. This causes platelets in the blood to clump together and form a blood clot. The clot blocks the flow of blood. Aspirin quiets the inflammation within plaques that leads to rupture. Aspirin also prevents platelets in the blood from clumping together and forming clots.

Dozens of studies involving tens of thousands of people have shown that daily low-dose (81 milligram) aspirin reduces the risk for a repeat heart attack or stroke. But aspirin also has risks. For one, it does increase the risk of minor bleeding. Cuts may bleed a little longer than usual. Bruises, which happen when blood leaks out of small vessels after an injury, may also be more noticeable.

Aspirin also hinders helpful substances that protect the delicate lining of the stomach. This can lead to stomach upset or bleeding in the stomach and intestines. As a result, a person can become anemic. More serious bleeding can lead to black, tarry stools. In rare cases, you may vomit blood.

For both men and women, gastrointestinal bleeding and hemorrhagic (bleeding) stroke are the main risks of aspirin. That’s why the U.S. Preventive Services Task Force recommends low-dose, rather than regular-strength, aspirin to prevent a repeat heart attack. Low-dose aspirin seems to work just as well as higher doses, with fewer bleeding problems.

The risk of bleeding complications rises with age. Aspirin-induced bleeding is also more likely to occur in people who have a history of uncontrolled high blood pressure, ulcers or bleeding problems. The risk is also higher in people who regularly take nonsteroidal anti-inflammatory drugs such as ibuprofen (Advil, Motrin), or the blood thinner warfarin (Coumadin). If you fall into any of these categories, talk to your doctor. Together, you can weigh the risks and benefits of low-dose aspirin for you.

In theory, taking aspirin with a protective coating (enteric-coated aspirin) should help avoid ulcers and other stomach-related side effects. However, I don’t think the evidence for this is very strong.

I’ve never had a heart attack, but I do have atherosclerosis of the arteries of my heart. I take low-dose aspirin every day. That’s because I am sure the benefits outweigh the risks for me.