Evaluation of L-Arginine Reactivity in Comparison with Flow-Mediated Dilatation and Intima-Media Thickness

Recently, L-arginine reactivity has been used for evaluation of cerebral endothelial impairment. However, the diagnostic potential of the method is still unknown. The aim of the study was to establish the sensitivity and specificity of L-arginine reactivity and compare this method with flow-mediated dilation (FMD) and intima-media thickness (IMT). L-arginine reactivity, FMD and IMT were determined in patients with arterial hypertension (AH) and presumed endothelial impairment (41 patients, aged 60.9 ± 7.4 y) and 21 age- and gender-matched healthy controls. The relative increase in the mean arterial velocity after a 30-min i.v. infusion of L-arginine (dvm(L-arg)) was ascertained by TCD. FMD of the brachial artery after hyperaemia and IMT of the common carotid artery on both sides were determined. The diagnostic value of the methods was assessed using receiver-operating-characteristic (ROC) analysis. In patients with AH, dvm(L-arg), FMD and IMT were diminished (11.5% ± 8.9%; 3.8% ± 4.8%; 0.82 ± 0.16 mm) compared with the healthy controls (20.5% ± 9.9%; 7.9% ± 6.0%;0.64 ± 0.15 mm) (p ≤ 0.01). The optimal cut-point for L-arginine reactivity of 0.22 yielded a 40% sensitivity and 93% specificity, which was comparable to the other two methods. For all three methods, the area under the ROC curves differed significantly from 0.5 (0.694; p = 0.013 for dvm(L-arg), 0.784; p ≤ 0.01 for FMD, 0.827; p ≤ 0.01 for IMT). Cerebrovascular reactivity to L-arginine is a valuable method for determination of cerebral endothelial function. The diagnostic value of the three methods is comparable. (E-mail: janja.pretnar@kclj.si)