Abstract WP137: Carotid Distension And Remodeling Is Associated With The Aorta-carotid Stiffness Gradient

Abstract

Background: Recent studies have suggested that the arterial stiffness gradient between the aorta and cerebrovasculature, versus aortic stiffness alone, better predicts incidence of cerebrovascular disease, due to increased transmission of pulsatile energy to the cerebral microcirculation. Our aim was to evaluate the association of structural and functional alterations in the carotid artery with the aorta-carotid stiffness gradient versus using aortic stiffness alone. Methods: We evaluated vascular measures in 29 subjects (50±2.4 yrs, range 33–75 yrs, 65.5% women). Carotid pulse wave velocity (an index of stiffness, using the Bramwell-Hill equation), intima-media thickness (cIMT), cIMT-lumen ratio, and strain were calculated from Doppler ultrasound images. Carotid-femoral PWV (cfPWV) was calculated using the distance between the carotid and femoral sites and the timing of the velocity upstrokes relative to the R-wave on simultaneous electrocardiography. The aorta-carotid stiffness gradient (cf/c) was estimated as the ratio of cfPWV to carotid PWV. Blood pressures were taken as the average of two resting measurements prior to testing. The cf/c ratio was log-transformed to account for positive skewness. Results: In univariate analysis, both cfPWV and log(cf/c) were associated with carotid strain (β=-0.76 and β=-15.91 respectively; both p<0.05). The cIMT-lumen ratio was associated with cfPWV (β=0.0049, p=0.019) but not with log(cf/c) (p=0.125). After adjustment for age, sex, BMI and SBP, the association between cfPWV and carotid strain was nonsignificant (p>0.05) while log(cf/c) remained independently associated with carotid strain (β=-12.69, p<0.05). In the adjusted model, both cfPWV and log(cf/c) were independently associated with cIMT-lumen ratio (β=0.0059 and β=0.082 respectively, both p<0.05). Conclusion: After adjustment, cfPWV and cf/c were associated with increases in the cIMT-lumen ratio, an indicator of inward remodeling. However, only cf/c was associated with carotid strain, a measure of vessel distension and an index of vessel stiffness. These results suggest that, compared to aortic stiffness alone, the aorta-carotid stiffness gradient may be a more robust indicator of alterations in carotid structure and function.