Objective To assess left ventricular global systolic function in breast cancer patients after epirubicin chemotherapy by two-dimensional speckle tracking imaging (2D-STI).Methods Thirty women with histologically confirmed breast cancer were prospectively studied.Two-dimensional images were recorded from the apical four-,two-chamber,long-axis views,and from basal,the papillary muscles and apical LV short-axis.Then the images were stored for off-line analysis of 2D speckle-tracking myocardial strain.Global peak longitudinal,radial and circumferential 2D systolic strain (GLS,GRS,GCS) and strain rate were measured within 1 week before and within 1 week after 4 cycles of chemotherapy (every 21 days for 1 cycle,4 cycles spend 3 months) and the cumulative dose of the drug was 270-400 mg/m2.Results GLS and GRS were significantly reduced after 4 cycles of treatment.GLS and GRS decreased from-19.7％to-18.7％ and 33.23％ to 30.13％,respectively(P ＜0.05).In contrast,conventional echocardiographic parameters,left ventricular global peak systolic strain rate and GCS did not show significant changes throughout follow-up (P ＞ 0.05).Conclusions 2D-STI is valuable for early monitoring left ventricular global systolic function after epirubicin chemotherapy,which has the application value of guiding the early clinical intervention and estimating prognosis.