Safety of Continuing Trastuzumab for Mild Cardiotoxicity: A Cardiovascular Magnetic Resonance Imaging Study

The safety of continuing human epidermal growth factor receptor 2 (HER2)-targeted therapy in women with mild cardiotoxicity remains unclear. We performed a retrospective matched cohort study of 14 patients with human epidermal growth factor receptor 2-positive breast cancer receiving sequential anthracycline and trastuzumab therapy, nested within the Evaluation of Myocardial Changes During Breast Adenocarcinoma Therapy to Detect Cardiotoxicity Earlier With MRI (EMBRACE-MRI) trial. Among patients who developed cardiotoxicity and were treated with heart failure therapy, we compared those who had trastuzumab therapy interrupted to a matched cohort who continued trastuzumab therapy. By a median of 2.5 years of follow-up, no significant differences were present between the groups in the proportion with magnetic resonance imaging-measured left ventricular ejection fraction < 40%, magnetic resonance imaging-measured left ventricular volumes, left ventricular ejection fraction, edema, fibrotic markers, cardiopulmonary fitness, or quality of life.