Decreased nitrate-mediated dilatation in patients with coronary artery ectasia: an ultrasonographic evaluation of brachial artery

Abstract

Coronary artery ectasia has been defined as localized or diffuse nonobstructive lesions of the epicardial coronary arteries with a luminal dilation exceeding the 1.5-fold of normal adjacent segment or vessel diameter. Although coronary artery disease is supposed to be responsible for more than 50% of coronary ectasia, the precise pathology of coronary artery ectasia is not clearly understood. The brachial artery ultrasound test for flow-mediated endothelial-dependent vasodilatory function includes administration of sublingual nitrates to examine the vasodilating effect of an exogenous source of nitric oxide. In the present study, we aimed to compare flow-mediated and nitrate-mediated responses of brachial artery in patients with coronary artery ectasia and patients with coronary artery disease. Thirty-six consecutive patients with coronary artery ectasia in combination with coronary artery disease and 42 age-matched and sex-matched patients with coronary artery disease alone were included in the study. Flow-mediated and nitrate-mediated dilatations were measured in all patients using a high-resolution B-mode ultrasonographic system. Baseline brachial artery diameters in patients with coronary artery ectasia were not statistically different from those in patients with coronary artery disease (4.2+/-0.6 vs. 4.0+/-0.6 mm, respectively, P=0.16). Although the forearm flow-mediated dilatation of the patients with coronary artery ectasia did not differ from that of patients with coronary artery disease alone (5.5+/-3.8 vs. 4.8+/-3.6%, respectively, P=0.41), nitrate-mediated dilatation was significantly lower than that of patients with coronary artery disease alone (7.9+/-5.2 vs. 10.9+/-5.4%, respectively, P=0.02). We have shown that patients with coronary artery ectasia have decreased nitrate-mediated response of brachial artery compared with patients with coronary artery disease alone, suggesting more severe dysfunction or, possibly, destruction of the media layer in coronary artery ectasia than in coronary artery disease.