BACKGROUND: Although it is known that trastuzumab causes cardiotoxicity, its 
extent and reversibility are still in question. Earlier studies have not 
evaluated consecutive patients with reproducible nuclear ventriculography.
OBJECTIVE: We sought to evaluate the baseline characteristics which predispose 
patients to increased risk of trastuzumab cardiotoxicity and to determine the 
natural history of the cardiotoxicity.
METHODS AND RESULTS: Left ventricular ejection fraction (LVEF) was measured in 
76 women aged 36-73 years who had been treated with trastuzumab at the 
University of Maryland Greenebaum Cancer Center. LVEF was determined at baseline 
and then 3, 6, 9, and 12 months after treatment initiation. Cardiotoxicity was 
defined as ≥ 16% decrease in LVEF or ≥ 10% decrease in LVEF to <50%. There were 
no differences in comorbidities, earlier treatment, or demographics between 
patients with and without trastuzumab-induced cardiomyopathy except that African 
Americans were more likely to develop decreased LVEF (P < .05). Twenty-one 
patients (28%) met criteria for cardiotoxicity. Four of those patients were 
continued on trastuzumab and 17 patients had therapy withheld at some point. 
Only 1 patient developed symptomatic heart failure requiring inpatient 
hospitalization. LVEF improved in most patients regardless of whether or not 
trastuzumab was continued.
CONCLUSIONS: Decreased LVEF while undergoing trastuzumab therapy occurs 
frequently and is usually reversible. African Americans had a higher risk of 
developing decreased LVEF. These findings raise clinically important questions 
as to whether it is necessary to discontinue trastuzumab for asymptomatic 
decrease in LVEF and whether African Americans are more predisposed to a 
decrease in LVEF while receiving trastuzumab. Further studies carefully 
assessing LVEF should address these hypotheses.