【Abstract】 Objective Two-dimensional ultrasonic speckle tracking imaging (2D-STI) was used to evaluate the early changes of left ventricular and right ventricular systolic function in patients with breast cancer. To explore its clinical value in evaluating early subclinical cardiotoxicity associated with chemotherapy with trastuzumab. Methods A total of 89 patients with breast cancer who were diagnosed in our hospital and received trituximab chemotherapy were analyzed retrospectively. there were 3 chemotherapy cycles and one chemotherapy cycle was 3 weeks. The baseline level before chemotherapy (T0), the first cycle (T1), the second cycle (T2) and the third cycle (T3) were examined by echocardiography, and the routine echocardiography parameters were measured. The global longitudinal peak strains (LVGLS and RVGLS) of left ventricle and right ventricle were measured by 2D-STI. Cardiotoxicity is defined as a decrease in left ventricular ejection fraction, which is less than 10% of the baseline level. With the occurrence of cardiotoxicity in the course of chemotherapy as the clinical outcome, the working characteristic (ROC) curve and Logistic regression analysis were used to analyze the predictive value of the parameters to the early (T1) cardiotoxicity associated with chemotherapy. Results 22 patients (24.7%) had cardiotoxicity during the chemotherapy cycle (cardiotoxicity group) and 67 patients (75.3%) had no cardiotoxicity (non-cardiotoxicity group). In patients with cardiotoxicity, T2 LVEF was lower than 18% of the baseline level, while LVGLS and RVGLS were significantly lower than the baseline level in T1 and T2. ROC curve and Logistic regression analysis showed that T1 RVGLS combined with LVGLS was the best index to predict early subclinical cardiotoxicity associated with chemotherapy in breast cancer. The diagnostic sensitivity and specificity were 98% and 75%, respectively. Conclusion In patients with breast cancer who had no significant decrease in left ventricular ejection fraction (LVEF), LVGLS and RVGLS in stage T1 had been decreased, 2D-STI technique is helpful for the early detection of chemotherapy-related subclinical cardiotoxicity.