Noninvasive determination of endothelium-mediated vasodilation as a screening test for coronary artery disease: Pilot study to assess the predictive value in comparison with angina pectoris, exercise electrocardiography, andmyocardial perfusion imaging

Background Peripheral endothelial dysfunction (ED) quantified by the determ ination of flow-mediated dilation (FMD%) of the brachial artery with the us e of high-resolution ultrasound is an early marker of atherosclerosis. Alth ough a positive correlation with coronary artery disease (CAD) has been rep orted, the unanswered clinical question is the validity of FMD% as a screen ing test in patients with clinical suspicion of CAD. Thus the aim of this s tudy was to determine the predictive value of FMD% compared with angina pec toris, exercise electrocardiography, and myocardial perfusion imaging. Methods and Results In this pilot study, we measured ED in 122 patients sch eduled for coronary angiography by using high-resolution ultrasound (13 MHz ). We defined ED as FMD% less than or equal to 4.5%. The presence of CAD wa s defined as angiographically detectable atherosclerotic vessel alterations of any degree. Exercise electrocardiography and myocardial perfusion imagi ng had been performed on an outpatient basis. Statistical analysis was cond ucted by analysis of variance and Mantel-Haenszel chi-square test. Patients with CAD (n = 101) had a significantly lower FMD% than patients without CA D (n = 21; 3.7% +/- 4.1% vs 7.01% +/- 3.5%, P < .001). A sensitivity of 71% , a specificity of 81% with a positive predictive value of 0.95 (72 of 76), and a negative predictive value of 0.41 (17 of 46) was calculated. In comp arison to angina pectoris (sensitivity 95%, specificity 47.6%), exercise el ectrocardiography (sensitivity 82.4%, specificity 57.1%) and myocardial per fusion imaging (sensitivity in our study group 100%) had the best specifici ty, and a high sensitivity for FMD% was found. Conclusions The determination of ED was found to be a sensitive and specifi c screening test to predict the presence of CAD. Because this is a noninvas ive, nonradioactive, and cost-effective approach, ii warrants further evalu ation to determine its value in daily clinical practice as an additional sc reening test in the diagnosis of CAD.