Currently, serial MUGA scans are the imaging modality of choice for monitoring cardiotoxicity. However, MUGA scans only measure LVEF at the cost of ionizing radiation and considerable inter-study variability, and do not reliably detect cardiomyopathy. CMR is a highly accurate technique and represents a promising imaging alternative. Because CMR is now considered the gold standard for measuring LVEF and subclinical alterations in cardiac structure and function, it will be used in this prospective observational pilot study to determine its effectiveness for monitoring cardiotoxicity in patients receiving trastuzumab. Serial CMR will be compared to serial MUGA scans, as they are routinely used for LVEF monitoring with trastuzumab therapy, in standard practice. Cardiac biomarkers will also be measured in relation to CMR and MUGA scans. Furthermore, we will determine the long-term clinical and prognostic implications of trastuzumab-induced cardiotoxicity detected by these various methods.
This will be a double-blinded prospective observational pilot study of breast cancer patients with overexpression of HER2 on breast pathology (using either immunohistochemistry \[IHC\] and/or fluorescence in-situ hybridization \[FISH\]), who have never received trastuzumab before, who will be treated with trastuzumab.
