Cardio-Ankle Vascular Index and Heart-Thigh β-Stiffness Index Associations with Cardiac Mechanics: The Multi-Ethnic Study of Atherosclerosis

Introduction: Large artery stiffening is associated with cardiac functional/structural abnormalities. We aimed to investigate the associations of the cardio-ankle vascular index (CAVI) and the heart-thigh β-stiffness index (htβ) with echocardiographic parameters. Methods: CAVI and htβ were measured in the 6th examination of the Multi-Ethnic Study of Atherosclerosis. Echocardiography (2-dimensional, Doppler, speckle-tracking) was performed during the same examination. Linear, multinomial, and restricted cubic spline regressions adjusted for demographic and clinical factors were used. Continuous variables were standardized in all models to derive β per 1-SD changes. Results: Among 2,958 participants (mean age 73.5 ± 8.3 years, 47.1% female), both CAVI and htβ were associated with a lower left ventricular (LV) ejection fraction (LVEF; CAVI: β = −0.05, p = 0.013; htβ = β = −0.06, p = 0.003) and global longitudinal strain (CAVI: β = −0.10, p < 0.001; htβ = β = −0.12, p < 0.001). CAVI was associated with a lower E velocity (β = −0.10, p < 0.001), eʹ (β = −0.05, p = 0.012), E/eʹ ratio (β = −0.06, p = 0.004), and lower early diastolic strain (β = −0.06, p = 0.002). Additionally, CAVI was associated with reduced right ventricular free wall strain, even after adjusting for LVEF and LV mass index (β = −0.06, p = 0.005). We observed inverse associations between htβ (but not CAVI) and left atrial booster (β = −0.05, p = 0.022) and reservoir (β = −0.07, p <0.001) strain. With LVEF ≥50%, relationships with LV longitudinal function, right ventricular strain, and left atrial function were similar. Conclusion: In a multi-ethnic population, higher values of CAVI and htβ were associated with decreased LV systolic and diastolic function, even among participants with preserved LVEF. Further studies should assess the effects of reductions in arterial stiffness and pulsatile load in heart failure with preserved ejection fraction.