Alternatives exist in testing for heart disease

Q. I have recently developed chest pain when I exercise. My doctor wants me to have a nuclear stress test to check my arteries for blockages. I would like to limit my exposure to radiation. Are there other tests that could be done instead?

A. There are many causes of chest pain besides heart disease. (I have listed the most common ones on my website, AskDoctorK.com.) Clearly, however, your doctor is concerned that you may have coronary artery disease (atherosclerosis causing blockages in the arteries of your heart), with the accompanying chest pain called angina. When a part of your heart muscle is not getting enough blood to work as hard as it is being asked to, it “cries out in pain.” That's angina.

Typically, the next step in testing would be an exercise stress test. The exercise is usually on a treadmill or a stationary bicycle. People who have trouble exercising (such as people with bad arthritis) can be given a medicine that makes the heart beat faster and harder.

However the heart is made to work harder, there are several ways of measuring if the heart muscle is under strain: an electrocardiogram, a nuclear stress test or an echocardiogram.

An electrocardiogram pattern changes when heart muscle is under strain. In a nuclear stress test, a slightly radioactive chemical is injected into your blood, travels to your heart, and identifies areas of heart muscle that have a poor blood supply. A stress echocardiogram uses ultrasound to “see” the motion of the heart. When blood flow through the coronary arteries is limited, part of the heart wall moves differently.

I consulted with my colleague, Dr. Richard Lee, a cardiologist and associate editor of the Harvard Heart Letter, to get his thoughts about these alternatives. He said that stress echocardiography may be a bit less sensitive -- it may not pick up quite as many cases of heart disease as nuclear stress tests. And it is more dependent on the expertise of the physician interpreting the test. But it doesn't involve radiation.

In contrast, nuclear stress tests may more often be “abnormal” even though a person doesn't really have heart disease. And it does involve radiation.

The American College of Cardiology and American Heart Association have published guidelines for doctors as to when it is best to use these different types of stress tests.

You asked about radiation exposure, so let's put that in perspective. Each year, the average person receives about 3 millisieverts (mSv) of background radiation from naturally occurring sources. This amount has little effect on health. A nuclear stress test exposes you to between 6 and 17 mSv of radiation. That's not much, not if you need the information to protect your health.

Ÿ Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: AskDoctorK.com.