Enhanced coronary calcification determined by electron beam CT is strongly related to endothelial dysfunction in patients with suspected coronary artery disease

Background: Coronary artery calcification determined by electron beam CT (EBCT) is strongly associated with total plaque burden but is not related to systemic vascular inflammation. Aims: We sought to test the hypothesis that enhanced coronary artery calcification, a marker of atherosclerosis and plaque burden, was related to endothelial dysfunction in patients with suspected coronary artery disease (CAD). Methods and results: One hundred twenty-four subjects with suspected CAD were enrolled. Coronary artery calcification was detected by EBCT. A noninvasive method of brachial ultrasound was used to measure endothelium-dependent flow-mediated vasodilation (FMD) and endothelium-independent nitroglycerin-mediated vasodilation (NMD). Serum high-sensitivity C-reactive protein (hsCRP) and monocyte chemoattractant protein-1 (MCP-1) levels were also determined. Of the 124 patients, the calcium scores ranged from 0 to 4,394. All subjects were classified into three groups according to coronary calcium scores: group 1, score 0 (n = 26); group 2, scores 1 to 199 (n = 50); group 3, scores ≥ 200 (n = 48). There was an inverse association between the degree of coronary artery calcification and the endothelium-dependent FMD in the three groups (6.9 ± 0.6% vs 5.3 ± 0.3% vs 3.7 ± 0.3%, respectively; p < 0.001) but not the endothelium-independent NMD. Besides, no significant difference in serum levels of hsCRP and MCP-1 were found among the three groups. However, both the serum levels of hsCRP and MCP-1 were correlated significantly with endothelium-dependent FMD (r = -0.211, p = 0.019; and r = -0.188, p = 0.037, respectively). By multivariate analysis, enhanced coronary calcification was a strong independent predictor of endothelial dysfunction (p < 0.001). Conclusion: Enhanced coronary artery calcification strongly predicted endothelial dysfunction in patients with suspected CAD. Also, serum levels of hsCRP and MCP-1 were significantly correlated with endothelial function. These findings suggested that both calcium deposition and inflammation were involved in endothelial dysfunction.