The Use of Shear Rate-Diameter Dose-Response Curves to Assess Endothelial Function

The brachial artery flow-mediated dilation test (FMD) is the noninvasive gold standard used to test endothelial function. Reduced FMD is an early event in the development of atherosclerosis and provides a marker for predicting future cardiovascular disease events. However, the potential for this promising test is limited by poor reproducibility. Three major limitations associated with standard FMD methodology account for the majority of the poor reproducibility. Firstly, expressing FMD as a percentage limits statistical power. Secondly, studies often fail to account for the stimulus, i.e., shear stress. Lastly, peak diameters in response to reactive hyperaemia are short-lived and, therefore, hard to capture. To compensate for these limitations, we suggest t hat endothelial function be estimated using shear rate: diameter dose response curves. The use of dose-response curves could potentially improve measurement reliability and validity.