Balance the benefits and risks of aspirin for heart health

DEAR DOCTOR K: Heart disease runs in my family, and my doctor thinks I should take low-dose aspirin even though I don’t have heart disease now. What do you think?

DEAR READER: Your question seems simple enough, and I wish I had a simple answer. The problem is that aspirin, like virtually all medical treatments, has benefits and risks, and they are different for one person than for another. The main risk of aspirin is bleeding.

For some people, the decision to take aspirin is easy. If a person has coronary artery disease — blockage of the arteries of the heart — he or she should take aspirin. The same is true if someone has had the type of stroke caused by a blood clot (called an ischemic stroke). In these cases, the benefits from aspirin are far greater than the risks (unless someone has an allergy to aspirin, or a bleeding tendency).

Coronary artery disease (CAD) causes heart attacks, but many people who have this disease have never had a heart attack. If their doctor has told them that they have CAD, they should take aspirin — even if they have never had a heart attack. Why? Because it will greatly reduce their risk of ever having one.

So far, so good. Now comes the more complicated part. You could have CAD, or a similar disease of the arteries in the brain (which increases stroke risk), and not know it. You could have what’s called “silent” CAD. It hasn’t caused you any symptoms, so your doctor hasn’t checked for it. Unfortunately, silent CAD is common.

If your risk of having silent CAD is high, for you the benefits of aspirin are greater than the risks. If your risk of CAD is low, the risks of aspirin are greater than the benefits. In those at low risk, aspirin is more likely to cause bleeding in the stomach, intestines, joints and brain than it is to prevent a heart attack.

So how can you tell what your risk of having CAD is? You can actually do a good job of estimating it. We link to several online calculators on the Harvard Health Publications website: www.health.harvard.edu/147. If you don’t use the Web, have someone do it for you.

These calculators ask about your age, gender, cholesterol, smoking, blood pressure and other risk factors. Using that information, they calculate your risk of having a heart attack in the next 10 years. Recent research suggests that taking aspirin has the most benefit if your 10-year risk is above 10.6 percent. If it is below 6 percent, the benefits are small. My risk is currently 16 percent, and I take a daily aspirin. I also exercise every day and eat a healthy diet — most of the time.

But don’t start taking aspirin on your own: Talk to your doctor. The risk of bleeding complications from aspirin rises with age. Men are about twice as likely as women to have gastrointestinal bleeding. Your doctor will be able to help you weigh the benefits against the risks.

(This column is an update of one that ran originally in December 2011.)

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.