Peripheral augmentation index as a biomarker of vascular aging: An invasive hemodynamics approach

We compared two measures of vascular function obtained from digital volume waveforms with measures of target organ damage and novel invasive measures of vascular function as they relate to vascular aging. Aortic pulse pressure amplification, pulsatility, form factor and extent of coronary atherosclerosis (modified Gensini score) were obtained invasively in 59 patients undergoing left heart catheterization. Digital volume waveforms were captured via peripheral arterial tone (PAT) and used to derive augmentation index (AIx) and the pulse wave amplitude-reactive hyperemia index (PWA-RHI). AIx was associated with age (r = 0.50, p < 0.05) and aortic pulsatility (r = 0.45, p < 0.05) and inversely associated with estimated glomerular filtration rate (-0.29, p < 0.05) aortic pulse pressure amplification (r = -0.28, p < 0.05) and aortic form factor (r = -0.38, p < 0.05). AIx was slightly higher in patients with left ventricular hypertrophy (LVH) versus those without left ventricular hypertrophy (30 vs. 14%, p = 0.058). There was no association between AIx and Gensini score. PWA-RHI was not associated with age, estimated glomerular filtration rate or invasive vascular parameters and did not differ in patients with versus without LVH (p = ns). PWA-RHI was inversely associated with Gensini score (r = -0.32, p < 0.05). AIx derived from PAT is correlated with age-associated changes in vascular function and target organ damage but not coronary atherosclerotic burden. PWA-RHI is associated with coronary atherosclerotic burden but is not associated with target organ damage or other measures of vascular aging assessed in this study. Each parameter provides distinct insight into systemic vascular aging and target organ damage.