Abstract 12448: Is a Novel Aortic Stiffness Parameter Cardio-ankle Vascular Index Useful Predictor for Exercise Tolerance?

Abstract

Exercise intolerance is generally considered to be associated with left ventricular (LV) diastolic dysfunction. In addition, increased aortic stiffness has also been known as a restricting factor of exercise capacity. Recently, the cardio-ankle vascular index (CAVI) has been proposed as a new noninvasive parameter of aortic stiffness which is independent of blood pressure. CAVI = a[ρ/ΔP×[ln Ps/Pd] PWV²]+b (a, b, constant; ρ, blood density; ΔP, difference in systolic and diastolic pressure; Ps, systolic pressure; Pd, diastolic pressure; PWV, heart-ankle pulse wave velocity). Accordingly, we examined whether CAVI could detect exercise intolerance in patients with preserved left ventricular ejection fraction (LVEF).

Methods: Sixty one patients who referred to exercise stress testing for clinical reasons and had preserved LVEF were enrolled (age 68.3±10.4 years; male 67.2%). All patients were evaluated with standardized cardio-pulmonary exercise testing (CPX) including the analysis for oxygen uptake at peak exercise (peak VO₂). Before testing, B-type natriuretic peptide (BNP) level was measured and comprehensive Doppler echocardiography was carried out. Early diastolic mitral annular velocity (Ea) was also measured. Aortic stiffness was evaluated using the heart-ankle PWV and CAVI.

Results: Peak VO₂ significantly and inversely correlated with the PWV (r=-0.41, p=0.001), the CAVI (r=-0.36, p=0.004), and Ea(r=-0.47, p < 0.001). Peak VO₂ also had significant inverse correlation with age (r=-0.43, p<0.001), body mass index (r=-0.29, p =0.02), and log BNP(r=-0.37, p=0.02). In multivariate regression models for the peak VO₂, the PWV (β =-0.40, p<0.01) and Ea (β =0.33, p=0.02) were selected as determinants for peak VO2. In another model including CAVI but not the PWV, CAVI (β =-0.30, p=0.04) and Ea (β =0.37, p=0.02) were selected as determents for peak VO₂. The PWV and CAVI were significantly correlated each other (r=0.78, p<0.001).

Conclusion: Increased arterial stiffness was inversely correlated with exercise capacity. Both the PWV and CAVI have significant power to estimate peak VO₂. Elevated aortic stiffness as well as deteriorated LV relaxation is important to explain exercise intolerance in patients with preserved LVEF.