Relations Between Aortic Stiffness and Left Ventricular Structure and Function in Older Participants in the Age, Gene/Environment Susceptibility-Reykjavik Study

Abstract

Background 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. Methods and Results We performed magnetic resonance imaging of the aorta and LV in 347 participants (72 to 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 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 (B=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 (B=4.0±0.8 mL/SD, P<0.001), but not in women (B=−0.4±0.7 mL/SD, P=0.6). Conclusions 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.

Relations Between Aortic Stiffness and Left Ventricular Mechanical Function in the Community

“…The combination of aortic annulus displacement along with minimal movement of the aortic arch implies that there is considerable longitudinal stretch of the ascending aorta during systole 10, 11, 41. Aortic stretch increases from the beginning until the end of systole and imposes a progressive systolic load on the heart 9, 12. If the aorta stiffens, the heart must contract with greater long‐axis force in order to produce the same amount of aortic displacement; for a given LV contraction strength, a stiff aorta would be displaced and stretched less than a compliant aorta would.…”

“…The relation between aortic stiffness and diastolic function is often attributed to hemodynamic effects, while the relation between GLS and diastolic function has been attributed to recoil of contracted LV muscle fibers 49, 50. Recent studies have suggested that diastolic recoil of the aorta and left atrium, which are stretched during systole, facilitates LV filling and ejection 12, 51, 52, 53, 54, 55. The association between increased aortic stiffness and worse GLS observed in our study may relate to both the systolic and diastolic components of direct mechanical ventricular–vascular coupling and requires further study 48…”

“…During systole, longitudinal shortening of the LV produces aortic displacement8, 9, 10 and stretches the ascending aorta 11. The force required to produce longitudinal strain of the aorta represents an often overlooked form of direct mechanical load on the LV that may have important implications for the relation between aortic stiffness and LV systolic function, particularly in the long axis 11, 12…”

Association of Aortic Stiffness With Left Ventricular Remodeling and Reduced Left Ventricular Function Measured by Magnetic Resonance Imaging

“…Higher systolic work and a mismatch in the ratio between myocardial supply and oxygen demand could result in reduced cardiac systolic and diastolic performance. In addition, the recent study demonstrated that greater aortic stiffness is associated with reduced longitudinal stretch-related aortic work that might lead to lower early diastolic filling 10 . In the present study, increased aortic arch PWV was associated with LV systolic and diastolic dysfunction.…”

“…Identifying an association between increased aortic stiffness and impaired myocardial deformation parameters may elucidate potential mechanisms for impaired vascular-ventricular coupling in the pathogenesis of HF. Although several studies have explored the association of aortic stiffness and global ventricular dysfunction in hypertension participants 9 and the general population 10 , no studies have explored the association between aortic stiffness assessed by MRI and myocardial deformation in a large general population cohort. Thus, in the present study, we aim to determine the relationship of aortic arch PWV with LV remodeling (LV mass and volume) and LV function including myocardial deformation parameters (LVEF, circumferential strain, torsion, early diastolic strain rate) in a large multi-ethnic cohort.…”