Cardiotoxicity is one of the primary concerns when administering anthracycline chemotherapy agents, such as doxorubicin and daunorubicin. The risk of cardiotoxicity with these agents is related to the cumulative dose, and is increased in patients with preexisting cardiac disease with a low ejection fraction. In the general population, resting echocardiography is often used to evaluate ejection fraction but there is potential for significant variability in the results.
Radionuclide ventriculography, also known as a MUGA (multigated acquisition) scan, is typically used to monitor patients receiving cardiotoxic chemotherapy as it is a highly accurate and reproducible test for quantitating left ventricular ejection fraction. A radionuclide ventriculogram is generally performed at baseline before chemotherapy is initiated, and before each subsequent dose of chemotherapy. The therapeutic regimen is dependent on the baseline cardiac function, with anthracycline chemotherapy contraindicated in patients with baseline ejection fractions less than 30%, and modified dosing required for patients with baseline ejection fractions of less than 50%. A decrease in the ejection fraction by ten or more percentage points may warrant discontinuation of therapy.