Supplementary Material for: Assessment of Adjuvant Trastuzumab-Associated Cardiac Toxicity in Korean Patients with Breast Cancer: A Single-Center Analysis

<b><i>Background</i></b>: We performed this analysis to investigate the clinical presentation of trastuzumab-associated cardiac toxicity in Korean women. <b><i>Method:</i></b> 124 patients treated in a single institute from January 2006 to November 2011 with adjuvant trastuzumab therapy following primary surgery were identified from a database. We evaluated the cumulative incidence of cardiac toxicity, associated risk factors, and changes in cardiac function during trastuzumab treatment. <b><i>Results:</i></b> The median age of patients was 50 years (range 27-73). After 12 months of follow-up, the cumulative incidence of cardiac toxicity was 12.1% (grade I: 8.1%, grade II: 0.8%, grade III: 3.2%). In total, 4% of patients discontinued treatment due to cardiac dysfunction. The left ventricular ejection fraction (LVEF) recovered in all patients who discontinued or delayed treatment due to cardiac dysfunction following treatment discontinuation. The degree of the decrease in LVEF was large at 6 months after the initiation of treatment. A lower LVEF at baseline (<65%) was associated with cardiac toxicity. <b><i>Conclusions:</i></b> The low incidence of cardiac toxicity and the reversibility of cardiac dysfunction may validate the safety of trastuzumab treatment in Korean women with an acceptable baseline LVEF.