Purpose: Hypertrophic cardiomyopathy (HCM) is characterized by hypertrophy of the left ventricle, with markedly variable clinical manifestations and hemodynamic abnormalities. The purpose of this study was to analyze echocardiographic characteristics and left ventricular (LV) torsion in HCM. Methods: 10 patients with basal left ventricular outflow tract (LVOT) obstruction (group 1: 62.5 짹 9.8 years) and 12 patients with dobutamine induced LVOT obstruction (group 2: 61.6 짹 9.8 years) were analyzed in this study. In group 2, LVOT peak velocity was 1.4 짹 0.4 m/sec with dobutamine. Mitral early filling (E), atrial filling (A) velocity, E/A ratio, early diastolic velocity (E') and late diastolic velocity (A') of mitral annulus were measured. LV rotation, torsion and LV longitudinal strains were measured by 2 dimentional speckle -tracking imaging using off-line method. Results: Echocardiographic characteristics are listed in table. Peak rotation and torsion were decreased in group 1 patients (group1: 7.58 짹 1.95째, 1.88 짹 0.56 째/m sec and group 2: 10.89 짹 2.66째, 2.24 짹 0.58 째/m sec, p<0.05, respectively). Group 1 patients showed reduced longitudinal strain and strain rate compared with group 2 (P<0.05). There was linear correlation between torsion and E/E' (p<0.05). Conclusions: Reduced longitudinal strain and strain rate suggested decreased LV longitudinal function. LV rotation and torsion were significant decrease in HCM with LVOT obstruction patients, suggesting more abnormal systolic function.

	IVS (cm)	LVPW (cm)	EF (%)	E (m/s)	A (m/s)	E/A	E���/A���	E/E���	Baseline LVOT velocity* (m/s)
Group 1	1.9 짹 0.3	1.4 짹 0.4	72.0 짹 11.1	0.9 짹 0.3	1.0 짹 0.5	1.0 짹 0.7	0.6 짹 0.2	23.4 짹 7.3	3.9 짹 1.7
Group 2	1.2 짹 0.3	1.1 짹 0.2	65.8 짹 10.3	0.6 짹 0.2	0.7 짹 0.2	1.2 짹 0.6	0.5 짹 0.2	15.4 짹 5.7	1.4 짹 0.4