Aims: The aim of this study was to test the hypothesis that coronary microvascular endothelial dysfunction (CMED) is associated with epicardial coronary atherosclerosis.
Methods and results: We performed a cross-sectional analysis of a comprehensive invasive assessment of coronary physiology with a focus on endothelium-dependent coronary microvascular function and virtual-histology intravascular ultrasound (VH-IVUS) in a total of 148 consecutive patients with chest pain and angiographically normal coronary arteries or non-obstructive coronary artery disease (CAD). Endothelium-dependent coronary vascular reactivity was evaluated by graded doses of intracoronary acetylcholine (ACh). CMED was defined as a percent increase in coronary blood flow of ≤50% in response to ACh. Patients with CMED (n=87) showed more vulnerable plaque characteristics as compared to those without (n=61); they showed higher plaque burden in association with larger necrotic core volume and higher frequency of imaged arteries containing at least one VH-IVUS-derived thin-capped fibroatheroma (TCFA) (n=22 [25.3%] vs 5 [8.2%], p=0.008). Multivariate logistic regression analysis revealed that CMED was an independent predictor of VH-IVUS-derived TCFA (adjusted odds ratio 2.28 [95% confidence interval: 1.30-4.02], p=0.004).
Conclusions: Independently of conventional coronary risk factors, CMED was associated with vulnerable plaque characteristics in patients with non-obstructive CAD.