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 1, 2009, 
through January 1, 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 1 echo per patient.
CONCLUSIONS: Given the low incidence of clinically significant HF and cost of 
monitoring, less frequent monitoring may be justified.