Abstract 12723: Coronary Microvascular Endothelial Dysfunction is Associated With Plaque Vulnerability in Patients With Early Coronary Atherosclerosis.

Background: Epicardial coronary endothelial dysfunction is associated with development and progression of local coronary atherosclerotic lesion. However, the role of coronary microvascular endothelial function in the development of coronary atherosclerosis is largely unknown. The aim of the present study was to test the hypothesis that coronary microvascular endothelial dysfunction (CMED) is associated with epicardial atherosclerotic coronary artery disease (CAD). Methods and Results: 148 patients with chest pain, referred for the evaluation of coronary vasomotion and found to have angiographically normal coronary arteries or mild CAD (<40% stenosis), underwent invasive coronary endothelial function testing and virtual-histology intravascular ultrasound (VH-IVUS) of the left anterior descending coronary artery. Endothelium-dependent coronary vascular reactivity was evaluated by graded administration of intracoronary acetylcholine. CMED was defined as percent increase in coronary blood flow of ≤50% in response to a maximum dose of acetylcholine. Patients with CMED (n=87), as compared to those with normal microvascular endothelial function (n=61), had higher averaged epicardial plaque necrotic core area [0.07 (0.01-0.34) vs. 0.03 (0.00-0.17) mm2, p=0.016] and higher frequency of imaged arteries containing at least one VH-IVUS-derived thin-cap fibroatheroma (TCFA) [n=22 (25.3%) vs. 5 (8.2%), p=0.008] (Figure). After adjusting for age, gender and CAD risk factors, CMED was an independent predictor of VH-IVUS-derived larger averaged necrotic core area (β=0.176, p=0.033) and TCFA frequency (β=0.180, p=0.028). Conclusions: CMED is an independent predictor of larger necrotic core plaque area and higher TCFA frequency, both of which are characteristics of rupture-prone plaques. [ABSTRACT FROM AUTHOR]