Left Ventricular Twist Mechanics in Hypertrophic Cardiomyopathy Assessed by Three-Dimensional Speckle Tracking Echocardiography

Abstract

Left ventricular (LV) twist represents a phenomenon that links systolic contraction with diastolic relaxation and plays a major role in cardiac physiology; thus, the study of twist mechanics is of particular interest in hypertrophic cardiomyopathy (HC). Three-dimensional speckle tracking echocardiography (3D-STE) has the potential to overcome the limitations of 2-dimensional imaging and provide a greater understanding of LV twist in HC. We aimed to examine LV twist mechanics in HC using 3D-STE. Echocardiograms from subjects with a diagnosis of HC were examined for 3D-STE analysis. Age- and gender-matched healthy subjects were tested as a control group. Forty patients with HC (age 37 ± 16 years; 42.5% women) and 40 control subjects (age 35 ± 10 years; 42.5% women) were examined. Compared with the controls, the patients with HC showed increased peak LV twist (16.5 ± 4.7° vs 12.0 ± 3.9°, p <0.001) mainly because of increased apical rotation of those with LV outflow tract obstruction (obstruction, 12.7 ± 4.4° vs nonobstruction, 9.7 ± 2.8°, p = 0.02). In addition, the patients with HC displayed onset of torsion recoil occurring closer to the aortic valve closure (94 ± 6% vs 85 ± 6%, p <0.001; time normalized by the length of systole), limited completion of untwist during early diastole (31 ± 12% vs 62 ± 15%, p <0.001), and delayed peak untwist velocity (22 ± 7% vs 13 ± 9%, p <0.001; time normalized by the length of diastole). In conclusion, the evaluation of twist mechanics using 3D-STE provides novel insight regarding alterations in LV mechanics in patients with HC. Elucidating the characteristics of the wringing motion of the heart might help to broaden the understanding of the hyperdynamic contraction and impaired relaxation observed in these patients.