Abstract

Background: Patients with hypertrophic cardiomyopathy (HCM) exhibit a difference in left ventricular outflow tract (LVOT) obstruction, independently of basal septal thickness (BST). Some patients with HCM have a steeper left ventricle to aortic root angle than controls.

Objective: To test the predictors of the LV-aortic root angle and the association between LV-aortic root angle and LVOT obstruction using three-dimensional imaging.

Patients: 153 consecutive patients with HCM (mean (SD) age 46 (14) years, 68% men) and 62 patients with hypertensive heart disease of the elderly (all >65 years of age, 73 (6) years, 34% men) who underwent whole-heart three-dimensional cardiac magnetic resonance (CMR) angiography (1.5 T) and Doppler echocardiography. Forty-two controls (age 43 (11) years, 38% men) who underwent contrast-enhanced multidetector computed tomography and were free of cardiovascular pathology were also studied.

Main outcomes: LV-aortic root angle, BST and maximal non-exercise LVOT gradient were measured in patients with HCM and in hypertensive-elderly patients. Additionally, LV-aortic root angle and BST were measured in controls.

Results: The mean (SD) LV-aortic root angle was significantly different (p<0.001) in the three groups: HCM (134 (10)°), hypertensive-elderly (128 (10)°), control (140 (7)°). There was an inverse correlation between age and LV-aortic root angle in the three groups (all p<0.001): HCM (r = −0.56), hypertensive-elderly (r = −0.35), control (r = −0.48). On univariate analysis, in the HCM group, LV-aortic root angle (β = −0.34, p<0.001), age (β = 0.23, p = 0.01) and end-systolic volume index (β = −0.20, p = 0.02), but not BST (β = 0.02, p = 0.8), were associated with LVOT gradient. On multivariate analysis, only LV-aortic root angle was associated with LVOT gradient.

Conclusions: Patients with HCM have a steeper LV-aortic root angle than controls. In patients with HCM, a steeper LV-aortic root angle predicts dynamic LVOT obstruction, independently of BST.