Trastuzumab in Female Breast Cancer Patients With Reduced Left Ventricular Ejection Fraction

Background Trastuzumab is life‐extending therapy for breast cancer patients overexpressing the human epidermal growth factor receptor 2 (HER2+), but has known cardiotoxic risk. We sought to determine if trastuzumab can be administered to patients with reduced baseline cardiac function at no higher cardiotoxicity risk than in those with normal cardiac function at baseline. Methods and Results We performed a retrospective study of women treated with trastuzumab for human epidermal growth factor receptor 2 breast cancer at Mayo Clinic Rochester between January 1, 2000 and August 31, 2015 with pre‐ and on‐therapy echocardiograms available for review. A left ventricular ejection fraction (LVEF) <53% was considered abnormal, and a ≥10% decline in LVEF as evidence of cardiotoxicity based on the criteria of the American Society of Echocardiography. A total of 428 women were identified; 408 had a normal cardiac function (LVEF 63.4±5%) and 20 had an impaired cardiac function (LVEF 45.4±7%) before trastuzumab. Seven...