Most cancer centers perform routine monitoring of heart function during treatment with HER2-targeted therapies. The method used for monitoring and the frequency of tests depends on each case.
Imaging of the heart will take place before therapy begins to ensure a normal heart function and will be repeated every three months after the HER2-targeted agent is started. Over time, you may have the test done less often, and no monitoring is required after therapy is completed. That is because the risk of cardiotoxicity is greatest during HER2-targeted therapies and lower once these cancer treatments are stopped. More testing may be done if you develop symptoms that suggest heart failure.
Here are the tests most commonly used to monitor heart function and cardiotoxicity:
- Echocardiogram: An ultrasound of the heart is used to calculate ejection fraction, a measure of how well your heart is pumping. Also, echocardiograms provide information on heart size, the relaxation of the heart, and the function of heart valves. The test is widely available and does not involve any radiation exposure.
- Multigated acquisition (MUGA) scan: This test involves your receiving a radioactive solution through a vein and then having an X-ray. A MUGA is commonly used to assess ejection fraction.
- Cardiac Magnetic Resonance Imaging (MRI): Cardiac MRI provides detailed information on heart size and function. It is usually reserved for cases when the images from the echocardiogram are not good enough or more information is needed.
- Blood tests: Some providers also may monitor markers present in your blood to measure heart injury. This is not done routinely and is more likely to occur in patients with increased risk of cardiotoxicity from HER2-targeted therapies and may help to detect heart damage early. Commonly measured blood markers are cardiac troponin (TnI, TnT) or natriuretic peptides (BNP, NT-proBNP).