Prognostic Significance of Brachial Flow-Mediated Vasodilation

There is currently much research devoted to the study of vascular biology in intact humans. These efforts aim to translate findings from the basic science arena to a better understanding of the pathophysiology of atherosclerosis and its complications. Markers of vascular risk have been used as surrogate end points in treatment studies. More recently, long-term studies have emerged that speak to the prognostic significance of these novel markers with a goal of refining risk stratification approaches. C-reactive protein is an excellent example of such a marker, with many others being evaluated.1Article p 2390 The vascular endothelium is in a unique position to serve as a metric of atherosclerotic risk. The healthy endothelium is antiatherogenic through favorable paracrine effects on vasodilation, inhibition of leukocyte adhesion, platelet aggregation and coagulation, and promotion of healing via progenitor cells.2 However, because of its position in the vascular wall, it is also the target of hemodynamic and biochemical perturbations. This leads to endothelial dysfunction early in the course of the disease, a property that could be exploited for risk evaluation.Endothelium-dependent vasodilation is a nitric oxide–dependent process that has been well studied in humans. There are many methods of assessing conduit and resistance vessel function. Conduit vessel responses can be evaluated by measuring the change in vessel diameter in response to physiological (shear stress) or pharmacological (acetylcholine) stimuli. Ludmer and colleagues3 were among the first to describe the differences in coronary responses to acetylcholine between healthy subjects and those with vascular dysfunction. Although the study of the coronary circulation is probably still considered the gold standard, it is not ideally suited to large population studies because of its invasive nature and expense. Celermajer et al4 advanced the concept that the dilation of the brachial artery that occurred in response to …