Pressure-Corrected Carotid Stiffness and Young's Modulus: Evaluation in an Outpatient Clinic Setting

BACKGROUND Conventional measures for assessing arterial stiffness are inherently pressure dependent. Whereas statistical pressure adjustment is feasible in (larger) populations, it is unsuited for the evaluation of an individual patient. Moreover, statistical "correction" for blood pressure may actually correct for: (i) the acute dependence of arterial stiffness on blood pressure at the time of measurement; and/or (ii) the remodeling effect that blood pressure (hypertension) may have on arterial stiffness, but it cannot distinguish between these processes. METHODS We derived-assuming a single-exponential pressure-diameter relationship-3 theoretically pressure-independent carotid stiffness measures suited for individual patient evaluation: (i) stiffness index beta(0), (ii) pressure-corrected carotid pulse wave velocity (cPWV(corr)), and (iii) pressure-corrected Young's modulus (E-corr). Using linear regression analysis, we evaluated in a sample of the CATOD study cohort changes in mean arterial pressure (Delta MAP) and comparatively the changes in the novel (Delta beta(0), Delta cPWV(corr), and Delta E-corr) as well as conventional (Delta cPWV and Delta E) stiffness measures after a 2.9 1.0-year follow-up. RESULTS We found no association between Delta MAP and Delta beta(0), Delta cPWV(corr), or Delta E-corr. In contrast, we did find a significant association between Delta MAP and conventional measures Delta cPWV and Delta E. Additional adjustments for biomechanical confounders and traditional risk factors did neither materially change these associations nor the lack thereof. CONCLUSIONS Our newly proposed pressure-independent carotid stiffness measures avoid the need for statistical correction. Hence, these measures (beta(0), cPWV(corr), and E-corr) can be used in a clinical setting for (i) patient-specific risk assessment and (ii) investigation of potential remodeling effects of (changes in) blood pressure on intrinsic arterial stiffness.