Relations between aortic stiffness and left ventricular structure and function in older participants in the Age, Gene/Environment Susceptibility--Reykjavik Study.

Abstract

Left ventricular (LV) contraction displaces the aortic annulus and produces a force that stretches the ascending aorta. We hypothesized that aortic stiffening increases this previously ignored component of LV load and may contribute to hypertrophy. Conversely, aortic stretch-related work represents stored energy that may facilitate early diastolic filling. We performed MRI of the aorta and LV in 347 participants (72-91 years old, 189 women) in the Age, Gene/Environment Susceptibility-Reykjavik Study to examine relations of aortic stretch with LV structure and function. Aortic stiffness was evaluated as the product of Young's modulus and aortic wall thickness. Force was computed from Young's modulus and longitudinal aortic strain; work was the integrated product of force and annulus displacement during systole. LV mass and dynamic volume were measured using the area-length method. Filling was assessed from time-resolved LV volume curves. In multivariable models that adjusted for age, sex, height, weight, end-diastolic LV volume, augmentation index, end-systolic pressure, and cardiovascular disease risk factors, higher aortic stiffness was associated with increased LV mass (β=3.0±0.8% per SD, P<0.001; sex interaction, P=0.8). Greater stretch-related aortic work was associated with enhanced early filling in men (β=4.0±0.8 mL/SD; P<0.001), but not in women (β=-0.4±0.7 mL/SD; P=0.6). Higher aortic stiffness was associated with higher LV mass, independently of pressure. Higher stretch-related work was associated with greater early diastolic filling in men only. Impaired diastolic recovery of energy stored by systolic proximal aortic stretch may contribute to increased susceptibility to diastolic dysfunction in women.