\[Abstract\]ObjectiveTo evaluate the role of QRS dispersion(QRSD) in evaluating left ventricular function and the asynchrony of ventricular motion in patients with left buddle-branch block(LBBB). MethodsForty-two hospitalized patients with LBBB and 28 normal controls (group C) were included in the present study. The 42 LBBB patients were further divided into 2 groups: the isolated LBBB patients (group A, n=7) and LBBB patients with other organic diseases (group B, n=35). The indices of echocardiography and electrocardiogram were compared and analyzed among the three groups, including left ventricular ejection(LVEF), left ventricular end-diastolid dimension(LVEDD), E/A ratio, interventricular mechanical delay(IVMD), left ventricular systolic asynchrony index (TS-SD), QRSD, and QRS duration(QRSd). Multivariate correlation analysis was used to analyze the correlation of QRSD and QRSd with the indices of electrocardiogram and echocardiography in the two LBBB groups. ResultsAll the indices were significantly different between group B and group C (P<0.05), except for LVEDD in group A (P=0.145). All the indices were significantly different between group A and group B, except for QRSd (P=0.175). The QRSd and QRSD were negatively correlated with LVEF in the two LBBB groups, with the correlation coefficients being -0.310 (P=0.046) for QRSd and -0.341 (P=0.027) for QRSD; QRSD and TS-SD were positively correlated, with the correlation coefficient being 0.318 (P=0.040). The rest indices were not significantly correlated. ConclusionQRSD of ECG can be used for evaluating left ventricular systolic dysfunction in patients with LBBB. However, further studies are needed in order to determine its role in estimating the asynchrony of ventricular motion.