Ask the doctor: Do I need a thallium stress test every year?

Content provided by the Faculty of the Harvard Medical School

Ask the doctor: Do I need a thallium stress test every year?

Ask the doctor

Do I need a thallium stress test every year?

Q. Ever since my bypass operation in 1996, my cardiologist has me take a thallium stress test every year. I haven't had any heart-related trouble since the bypass, and the test results are always fine. I'm worried that the radiation from these tests is going to give me some kind of radiation-related cancer. What does this test tell my cardiologist? Do I really need it?

A. The danger from the minuscule amount of radiation involved in a thallium stress test isn't something you should worry about. No one has ever demonstrated that nuclear cardiology tests increase the risk for cancer, so the danger is trivial, if it exists at all. That's the good news. The bad news is that the need for you to have this test every year is probably equally nonexistent.

The use of a radioactive tracer like thallium during an exercise test allows a special camera to make clear pictures of heart tissue before, during, and after exertion. The images can show the extent of artery blockage, zones of damaged heart muscle, and whether angioplasty or a stent continues to hold open a once-narrowed coronary artery.

It is common practice for some cardiologists to order yearly nuclear cardiology tests for people like yourself who have had bypass surgery or angioplasty. That said, this practice goes against guidelines from the American College of Cardiology and the American Heart Association. They do not recommend routine testing for people who are feeling fine and are free of chest pain or other symptoms that indicate one or more narrowed arteries, whether or not they have had angioplasty or bypass surgery. The reason is simple: A positive test isn't reason enough to suggest another cardiac catheterization and angioplasty. If the test doesn't change anything, then why do it?

Your doctor may know something about you and your heart that I don't, and so may have a great reason for doing this test. You might point out that the guidelines do not recommend routine annual thallium tests for people who are free of symptoms, and see what he or she says.

— Thomas Lee, M.D. Editor in Chief, Harvard Heart Letter

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Last updated:	December 19, 2006

Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.

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