786-6 Brachial Artery Vasoactivity: Cold Pressor but not Flow-Mediated Responses Correlate with the Presence of Coronary Artery Disease

Abstract

Flow-mediated brachial artery vasoactivity is abnormal in patients with coronary artery disease and cardiac risk factors. Cold pressor coronary artery vasoactivity is abnormal in patients with coronary disease, but brachial artery responses have not been studied. The purpose of this study was to assess whether cold pressor and flow-mediated brachial artery vasoactivity correlate independently with the presence of coronary artery disease. We studied 50 men (27 clinically normal, 23 angiographically proven coronary artery disease) ranging from 23 to 59 years old. Using 7.5 MHz ultrasound, we measured brachial artery diameter and Doppler flow velocity at baseline, during contralateral ice water hand immersion (cold pressor), following five minutes of ipsilateral blood pressure cuff occlusion (flow-mediated) and following nitroglycerin administration. During cold pressor stimulation, mean brachial artery diameter increased 0.36 ± 2.93% in the normal subjects but decreased 2,38 ± 3.32% in the coronary disease subjects (p = 0.006). Cold pressor vasoactivity correctly predicted the presence of coronary disease in 76% of the subjects using a predetermined criterion. Mean flow-mediated diameterincreased 9.11 ± 6.01% and 6.58 ± 7.50% in the normal and coronary disease subjects, respectively (P ± NS), Responses to sublingual nitroglycerin were the same in the two groups. Using multiple stepwise regression analysis, cold-pressor vasoactivity was found to be dependent upon smoking status (p = 0.0002) and the presence of coronary disease (p = 0.04). In the 32 non-smokers undergoing assessment, the presence of coronary disease was the only significant determinant of cold pressor vasoactivity (p = 0.02). Flow-mediated vasoactivity was found to be dependent on smoking status (p = 0.005) and baseline brachial artery diameter (p = 0.02), Flow-mediated vasoactivity correlated with total cholesterol by univariate but not multivariate analysis. The associations of brachial artery vasoactivity with cardiac risk factors and coronary disease appear to be stimulus dependent. Cold pressor vasoactivity correlates more closely with the presence of coronary disease than does flow-mediated vasoactiVity, These findings suggest that abnormal cold pressor vasoactivity is a generalized vascular marker for atherosclerosis, but that flow-mediated vasoactivity correlates with the presence of risk factors.