Endothelial function assessment in atherosclerosis Comparison of brachial artery flow-mediated vasodilation and peripheral arterial tonometry

INTRODUCTION Endothelial dysfunction, characterized by the loss of nitric oxide bioavailability, is a key element in the pathogenesis of atherosclerosis and an important prognostic factor in cardiovascular diseases. Therefore, the development of reliable, safe, and noninvasive methods of endothelial function assessment is important for their use in cardiovascular risk stratification. Brachial artery flow-mediated dilation (FMD) is widely used in research but technical difficulties and problems with calibration between laboratories limit its clinical use. Reactive hyperemia-peripheral artery tonometry (RH-PAT, EndoPAT) has been developed as a simpler, cheaper, and potentially more reproducible method. OBJECTIVES We aimed to investigate associations between RH-PAT and FMD in relation to atherosclerotic risk factor profile. PATIENTS AND METHODS The study involved 80 subjects (52 men, 28 women) aged 43.6 +/- 14.8 years, with moderate-to-low cardiovascular risk (mean SCORE, 2.2% +/- 2%), in whom FMD, RH-PAT, and intima-media thickness (IMT) were determined. RESULTS The reactive hyperemia index (RHI) measured by RH-PAT correlated with FMD (r = 0.35, P < 0.01). However, no significant correlation was observed between RHI and IMT, SCORE, or the number of classical atherosclerotic risk factors (hypertension, smoking, diabetes, hypercholesterolemia), while FMD was significantly correlated with IMT (r = -0.53, P < 0.001), risk factors (r = -0.55, P < 0.05), and SCORE (r = -0.4, P < 0.05). CONCLUSIONS Despite its technical requirements, FMD is a more sensitive method than RH-PAT in evaluating the effect of classical atherosclerotic risk factors on vascular endothelial function. Microvasculature response during RH-PAT needs to be further studied, including the assessment of nonendothelial factors that may affect the measurements, before RH-PAT becomes the universal tool for the evaluation of the endothelial cells.