Serial changes of layer-specific myocardial function according to chemotherapy regimen in patients with breast cancer

AIMS: Chemotherapy-induced cardiotoxicity (CIC) is a significant complication, meanwhile myocardial damage might differ depending on chemotherapy agents and their timing. The aim of this study was to evaluate serial changes of layer-specific myocardial function in patients with breast cancer and their differences by the development time of CIC and chemotherapy agent. METHODS AND RESULTS: A total of 105 consecutive patients with breast cancer (age: 52.3 ± 9.3 years) were enrolled. Chemotherapy-induced cardiotoxicity occurred in 20 (19%) patients during 6 months. Endocardial and midmyocardial functions decreased in patients with or without CIC, with patients with CIC showing greater decreases during follow-up. Global longitudinal strain (GLS) change at 3 months was the most sensitive parameter to detect CIC. When new development of CIC was analysed at 6 months, GLS was reduced earlier than the decrease of left ventricular ejection fraction. In patients with CIC who were treated with anthracycline-based regimen for 3 months, endocardial GLS markedly decreased at 3 months and continued to decrease until 6 months. Patients with CIC who received trastuzumab therapy after anthracycline therapy showed further reduction in endocardial GLS at the 6-month follow-up, which was not shown in patients with CIC who received taxane therapy subsequently. CONCLUSION: Myocardial function assessed by strain decreased in all patients with breast cancer receiving chemotherapy. The endocardial layer was the most vulnerable to chemotherapy-induced myocardial damage. Functional impairment was more profound in patients with CIC who received sequential anthracycline-trastuzumab chemotherapy. Thus, early evaluation of left ventricular function might be necessary for all patients with breast cancer to detect CIC.