Objective: LV apical rotation contributes to LV twist, which has been reported to play a vital role to maintain LV systolic and diastolic function. apical hypertrophic cardiomyopathy (ApHCM) is a unique disease with pathologic LV hypertrophy at the apex. We aimed to evaluate LV twist mechanics by torsion-volume curve and biplanr strain to determine the difference of LV twist in ApHCM patients. Methods: ApHCM patients (n=21) were consecutively enrolled and compared with normal controls. After a standard echocardiography, we scanned parasternal basal and apical short-axis planes to quantify LV rotations and LV twist. LV radial, circumferential and logitudinal strain was derived at septum and lateral to calculate the biplanar strains. Results: Compared with the normal controls, apical rotation was markedly decreased in ApHCM patients (p<0.001), but decreases in basal rotation were not significant. As a consequence, LV twist was significantly lower in ApHCM patients (p=0.007). Apical radial (P=0.01) and biplanar (p<0.001) strains in ApHCM patients were also significantly decreased. Torsion-volume curve showed the decreased in slope of linear systolic phase and early rapid untwisting phase and loss of inflection point. Conclusion: LV twist in ApHCM was significantly reduced due to a reduction in apical rotation. Regional changes in ApHCM may modify the influence of apical rotation on global LV twist. Loss of early rapid untwinsting shows the loss of early diastolic suction, which leads to the diastolic dysfunction in ApHCM patients.