Trastuzumab products can cause cardiac dysfunction. The labeled monitoring schedule includes a baseline cardiac assessment with LVEF measurement by echocardiogram or MUGA scan and LVEF assessment at 3-month intervals during and at completion of therapy. Significant declines require treatment to be withheld and reassessed according to the label. Pulmonary, hepatic, and hematologic findings still require clinical monitoring, but the listed testing schedules do not replace required cardiac surveillance.
Clinical reasoning HER2 signaling contributes to cardiomyocyte survival. Blocking this pathway can reduce ventricular function, with added risk after anthracycline exposure.
Decision rule Establish baseline LVEF and repeat it at 3-month intervals during trastuzumab therapy; escalate symptoms of heart failure or a significant LVEF decline before further dosing.
Scenario 48-year-old female with HER2+ breast cancer starting trastuzumab with prior anthracycline exposure.
Left ventricular ejection fraction — The percentage of left ventricular blood volume ejected with each contraction, measured to monitor trastuzumab-related cardiac dysfunction.
Trastuzumab cardiotoxicity — A decline in left ventricular function or clinical heart failure associated with HER2-directed therapy.
Reversible cardiotoxicity — Trastuzumab cardiotox often improves with discontinuation, unlike anthracycline.