Objective-The purpose of the current study was to determine whether lipoprotein-associated phospholipase A 2 (Lp-PLA 2 ) is associated with coronary endothelial dysfunction and is a predictor of endothelial dysfunction in humans. Methods and Results-Patients (172) with no significant coronary artery disease (Ͻ30% stenosis) undergoing assessment of coronary endothelial function were studied. Endothelial function was assessed by the change in coronary blood flow and coronary artery diameter in

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... ponse to intracoronary acetylcholine. Plasma concentrations of Lp-PLA 2 were measured, and patients were divided into tertiles. Patients in tertiles 2 and 3 had a significantly lower change in coronary blood flow ( 63.8Ϯ73.2 and 32.0Ϯ71.7 versus 78.4Ϯ73.2%; PϽ0.001) and greater epicardial coronary artery vasoconstriction (Ϫ14.1Ϯ14.7 and Ϫ23.3Ϯ25.1 versus Ϫ9.5Ϯ15.2% mean diameter change; PϽ0.001) in response to acetylcholine. Patients with coronary endothelial dysfunction had significantly higher serum concentrations of Lp-PLA 2 than those with normal endothelial function (246.2Ϯ71.6 versus 209Ϯ56.7 ng/mL; Pϭ0.001). The odds ratio for coronary endothelial dysfunction in patients with Lp-PLA 2 in the highest tertile was 3.3 (95% CI, 1.6 to 6.6). Conclusions-Lp-PLA 2 is independently associated with coronary artery endothelial dysfunction and is a strong predictor of endothelial dysfunction in humans. (Arterioscler Thromb Vasc Biol. 2006;26:106-111.)