Clinical Utility of Routine Cardiac Monitoring in Breast Cancer Patients Receiving Trastuzumab.

Background: Trastuzumab targets the human epidermal growth factor receptor-2 (HER2). Cardiotoxicity is a potential adverse effect, manifesting as either an asymptomatic decline in left-ventricular ejection fraction or infrequently as largely reversible symptomatic heart failure (HF). Monitoring recommendations differ between product labeling and 2012 guidelines, and the clinical utility of serial cardiac monitoring in patients with metastatic breast cancer remains controversial. Objective: The objectives of this study were to describe the frequency of monitoring, incidence of symptomatic or asymptomatic HF, overall effect on treatment, and cost of monitoring for cardiotoxicity. Methods: We preformed an institutional review board approved retrospective chart review of breast cancer patients receiving trastuzumab from January I, 2009, through January I, 2014, at an academic medical center. Results: Out of 154 treatments, 72% were adjuvant, and 28% were metastatic. In the adjuvant setting, a mean of 4.5 (interquartile range [IQR] = 4-5) echocardiograms (echos) over a mean of 11.5 (IQR = 11-12) months were performed. In the metastatic setting, a mean of 3.1 (IQR = 1-5) echos over a mean of 20.2 (IQR = 9-31) months were performed. Symptomatic HF events occurred in 4 adjuvant (3.6%) and 2 metastatic patients (6.5%); 10 patients (6.5%) had a treatment interruption, with 9 (90%) tolerating restart of trastuzumab. Two patients (1.3%) changed treatment as a result of cardiotoxicity. Using population incidence of HER2-positive breast cancer, $13 million could be saved if monitoring were reduced by I echo per patient. Conclusions: Given the low incidence of clinically significant HF and cost of monitoring, less frequent monitoring may be justified.