Q

. After I had an abnormal electrocardiogram, my doctor wants me to have a nuclear stress test to check my arteries for any blockages. (I also have a left side bundle block.) What noninvasive test would give as much information (or almost as much) as a nuclear stress test?

I’ve had many scans, for this and that, so I would like to limit my exposure to radiation if possible.

A

. There are a number of options to test for coronary artery blockages. The gold standard is coronary angiography. But since it is invasive, requiring that a catheter be inserted into the heart, imaging tests are often used first to see if a coronary angiogram is needed.

The most common imaging tests are the nuclear stress test and the stress echocardiogram. The nuclear stress test uses a radioisotope to make blood flowing through the coronary arteries appear on a scanner, so it exposes you to radiation. A stress echocardiogram uses ultrasound to “see” the motion of the heart. When blood flow through the coronary arteries is compromised, part of the heart wall moves differently – a change that an experienced echocardiographer can detect. A stress echocardiogram does not use ionizing radiation; the small amount of energy delivered by medical ultrasound has never been shown to harm tissues.

The results of numerous studies comparing the accuracy of nuclear stress testing with stress echocardiography show that they are reasonably close. However, stress echocardiography is probably a bit less sensitive and more dependent on the expertise of the physician interpreting the test. Also, left bundle branch block can reduce the accuracy of either test.

Which test to select depends on an individual’s situation and the expertise of the available doctors. Even more options than these are available at major centers, including CT angiography, coronary MRI angiography, single-photon emission computed tomography (SPECT) myocardial perfusion imaging, and cardiac positron emission tomography (PET). Some of these deliver radiation; some don’t.

I suggest that you let your doctor know that you are concerned about radiation exposure and discuss the pros and cons of different tests in detail. – Richard Lee, M.D., associate editor, Harvard Heart Letter.

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