ABSTRACT Objective The changes of left ventricular function in patients with multiple myeloma（MM） with left ventricular ejection fraction（LVEF） reservation were analyzed by two-dimensional speckle tracking imaging（2D-STI） to explore its clinical value in evaluating early myocardial injury. Methods 72 patients with preserved LVEF who were clinically diagnosed as MM in our hospital were divided into two groups：the ventricular septal thickening group and non-thickening group（36 cases each），and 39 healthy controls were selected,Echocardiography and 2D-STI LS analysis were performed to obtain and compare the LS-related parameters of the myocardial segments (apical, middle and basal segments)and left ventricular layer-specific strain（endocardial, mid-myocardial and epicar-dial）.Pearson or Spearman correlation analysis was used to analyze the correlation between each strain parameter and BNP.The increase of brain natriuretic peptide（BNP） was taken as the standard of myocardial injury，receiver operating characteristic (ROC) curves were drawn to analyze the potency of each strain parameter to diagnose myocardial injury.Inter -and intraobserver reproducibility of each strain parameter was analyzed using the intraclass correlation coefficient (ICC)..Results The absolute value of global longitudinal strain in the endocardial layer(GLS-endo), Mid-myocardial layer(GLS-mid) and epicardial layer (GLS-Epi) were decreased in the interventricular septum thickening group compared with the normal control group or the non thickened interventricular septum group.The absolute values of LS values in the endocardial，middle and epicardial basal segments and middle segments of the thickening ventricular septum group decreased，The ratio of apical LS /（basal LS + middle LS） in each layer of myocardium increased .The differences were significant ( P< 0.05).The results of correlation analysis showed that in the septum thickening group，there was a positive correlation with BNP between GLS-Endo and LS in the basal segment of the endocardial，middle and epicardial layers（r=0.458，0.415，0.365，0.429，p=0.010，0.020，0.044，0.016）. The ROC curve analysis showed that the GLS-endo cutoff value of - 22.1% had the highest potency for diagnosing myocardial injury, with an area under the ROC curve of 0.825 (95% CI: 0.689-0.962, P = 0.001), sensitivity of 66.7% and specificity of 93.3%. The repeatability test showed high inter- and intraobserver reproducibility and reliability for GLS-Endo, GLS-Mid and GLS -Epi. .Conclusion The global and segmented LS of each layer of myocardium obtained by 2D-STI technology can sensitively identify myocardial injury in MM patients with LVEF preservation.LS in the basal segment of endocardial layer is more able to evaluate local myocardial injury and abnormal systolic function early, which can provide a reference for early clinical intervention.