Sestamibi and thallium stress tests; MIBI stress test

Nuclear imaging stress tests are very safe. The estimated risk of complications are only about 1 in 1,000 to 1 in 2,000 cases. These complications involve rare skin rashes, large fluctuations in blood pressure, arrhythmias, and difficulty breathing or asthma-like reactions. These, and any additional risks that may apply specifically to you, will be explained to you in advance by your doctor and by the health care provider performing the test.

Radiation exposure to radiotracers can be a concern for the nuclear lab staff, but not for patients undergoing an occasional nuclear imaging test.

Sometimes a thallium or sestamibi test produces heart image that looks like a defect, but its a pseudo-defect that gives a false positive test result (i.e., a falsely abnormal test). This is due to interference with the heart image from non-heart tissues such as the diaphragm (diaphragm attenuation), and, in women, the breast tissue ("breast attenuation").

When non-heart tissue attenuation is clearly the cause of an abnormal image, nothing additional needs to be done. If an attenuated image instead is thought to coincide with a true defect or area of ischemia (reduced blood flow), then your doctor may recommend additional testing such as a stress echocardiogram or a cardiac catheterization.