Abstract 17983: Ankle-Brachial Index Predicts Progression of Aortic Stiffeness

Abstract

Background: Arterial stiffness is associated with increased risk for adverse cardiovascular outcome. Ankle-brachial index (ABI) is a measure reflective of systemic atherosclerosis. Whether it can predict central aortic stiffness and its progression is unknown. As such, we investigated the impact of ABI on carotid-femoral pulse wave velocity (cfPWV) and aortic characteristic impedance (Z c ) in apparently healthy adults from the community. Methods: Participants were from the GENOA study without cardiovascular disease at baseline (December 2000 to September 2006) and completed follow-up (September 2009 to December 2012) assessment (n=358, 63%women, 69% hypertensive). ABI was measured by standard protocol at baseline. cfPWV was measured by applanation tonometry. Difference in log-cfPWV between two visits ([[Unable to Display Character: ∆]]log-cfPWV) was used to estimate progression of aortic stiffness. Z c was ascertained at 2 nd visit using carotid tonometry followed by echocardiography (Cardiovascular Engineering Inc., Norwood). Results: After a mean follow-up of 8.5±0.9 years, cfPWV increased from 9.3±2.4m/s to 11.1±5.0m/s. After adjusted for age, sex and time-interval between two visits, lower ABI was associated with greater [[Unable to Display Character: ∆]]log-cfPWV (β±SE:-0.41±0.15), and increased risk for higher log-cfPWV (β±SE:-0.38±0.12) and higher log-Z c at 2 nd visit (β±SE:-0.38±0.18) (all P≤0.04). Diabetes and renal function at baseline were predictors for higher cfPWV and Z c ; hypertension and metabolic syndrome were only predictors of cfPWV; while age and male gender were major predictors for [[Unable to Display Character: ∆]]log-cfPWV (all P≤0.04). The association of ABI with cfPWV or Z c remained significant after adjustment for these covariates (both P<0.05). Greater [[Unable to Display Character: ∆]]log-cfPWV was associated with increased risk for higher log-Z c ; longer time-interval amplified this effect (both p for [[Unable to Display Character: ∆]]log-cfPWV and [[Unable to Display Character: ∆]]log-cfPWV x time-interval ≤0.03). Conclusions: Lower ABI predicts progression of aortic stiffness, leading to both increased aortic wall stiffness (PWV) and greater aortic area-flow mismatch (Z c ), suggesting the impact of subclinical atherosclerosis on proximal aortic stiffening.