Abstract 16894: Association Between Flow Mediated Vasodilation and Coronary Artery Disease

Abstract

Introduction: Flow-mediated vasodilatation rate (FMD) is an ultrasound measurement often used to assess vascular endothelial function. Endothelial dysfunction causes coronary atherosclerosis by decreasing nitric oxide levels, which alters vasodilation and causes destabilization of established plaque. Hence, FMD has been proposed to be a surrogate marker of atherosclerosis severity and predictive of cardiovascular outcomes. Hypothesis: We intend to evaluate the relationship between the severity of Coronary Artery Disease (CAD) and FMD. We hypothesize that patients with lower FMD would have more severe CAD when compared to individuals with higher FMD. Methods: We identified 291 patients (169 [58%] male, mean age 59.6 ± 11.3 years), clinically referred for Coronary Artery Calcium(CAC) Scoring and Coronary Computed Tomography Angiography (CCTA) at our center. After informed consent, we measured brachial artery FMD using ultrasound (UNEXEF, Unex, Japan). CAC was measured using Agatston method. Segment Involvement Score (SIS; the total number of segments with any plaque), Segment Stenosis Score (SSS; the sum of maximal stenosis score per segment), Total Plaque Score (TPS; the sum of all segments plaque burden) were assessed using the 17-segment model with CCTA. We calculated the median FMD. We used multivariate regression analysis to analyze the association between FMD and the markers of CAD (i.e., CAC, TPS, SSS, SIS), after adjusting for confounding variables. Results: Median FMD in the group was 4.1% (25%-75%: 2.2-6.0). After multivariable analysis, individuals with FMD lower than 4.1% were noted to have significantly higher CAC (p=0.024), TPS (0.024), SSS (p=0.015) and SIS (p=0.010). (Table 1) Conclusions: We conclude that impaired FMD rate is an indicator of more severe coronary artery disease. Further studies to evaluate non-invasive ultrasound FMD measurement as a tool for predicting subclinical atherosclerosis and mechanisms are warranted. This could also serve to provide additive information for risk stratification of patients and cardiovascular outcomes.