Objective To assess left ventricular (LV) untwisting in patients with acute myocardial infarction(AMI) in different location by two-dimensional speckle tracking imaging(2D-STI),searching for sensitive parameter to evaluate the untwisting motion,to explore the impact of myocardial infarction(MI)location and number of MI segments on left ventricular untwisting movement.Methods Forty-one patient with AMI (AMI Group) were divided into two groups (anterior wall-anteroseptum group and inferior wall-posterior wall group) according to the MI location,and 31 age matched subjects were involved as the control group.Acquire the bull's eyes map of systolic strain (LPSS) values by automated function imaging(AFI)and locate the position and number of segments of MI by it.Access twist at aortic valve closure (AVCtw),twist at mitral valve open (MVOtw),peak twist velocity(PTV),untwisting rate in IVRT (Untw-R),peak untwisting velocity(PUV),time to peak untwisting velocity(TPUV) and half time of untwisting (UHT)with STI.Results Compared with control group,left ventricular ejection fraction (LVEF),global LPSS,PUV and Untw-R of AMI group decreased significantly (P ＜0.001),T-PUV (P ＜0.001) and UHT (P =0.028) increased significantly.The number of MI segments correlated with Untw-R (r =-0.420,P =0.006) significantly.There was no significant correlation between number of MI segments and UHT,PUV,TPUV.Untw-R in anterior wall-anteroseptum group were lower than inferior wall-posterior wall group(P =0.022).For PTV,PTW,T-Ptw,PUV,UHT and T-PUV,there was no significant difference between anterior wall-anteroseptum group and inferior wall-posterior wall group.Conclusions LV untwisting motion of AMI patients can be observed by 2D-STI.Untw-R is a sensitive parameter to evaluate the untwisting motion of AMI patients.The untwisting motion of AMI patients decrease significantly,even worse in anterior wall-anteroseptum AMI patients.