Objective To analyze the strains of patients with hypertrophic cardiomyopathy (HCM) by vector velocity imaging(VVI),and to identify abnormal early systolic function.Methods Forty patients with HCM (HCM group) and 25 healthy subjects (control group) were enrolled.Standard two-dimensional echocardiography was performed.Left ventricular ejection fraction (LVEF),diameters and wall thickness were measured.Peak systolic strains in all directions and their time to peak were analyzed off-line.Results ①All but the endocardial circumferential strain were apparently smaller in HCM group than those in the control group(P ＜0.000 1).The difference was greater in long axis than that in short axis.②The HCM group maintained the characteristics of strain gradient as the control group,including the endocardiumepicardium gradient with endocardial strains was significantly greater than epicardial ones and the base-apex gradient,among which epicardial longitudinal strain decreased from the base to the apex and endocardial circumferential strain increased toward the apex.③The HCM group suffered significant dyssynchrony in terms of strain and rotation,with greater changes in longitudinal than in short axis,in epicardium than in endocardium.Conclusions VVI offers an overall assessment of regional and global left ventricular systolic function,including longitudinal and circumferential strain.Moreover,it can be used to evaluate subclinical systolic dysfunction and dyssynchrony in patients with HCM.