Relationship between plasma oxidized low-density lipoprotein and the coronary vasomotor response to acetylcholine in patients with coronary artery disease

The present study examined the relation of plasma oxidized low-density lipo protein (LDL) levels to plasma LDL cholesterol levels and the impairment of endothelium-dependent coronary vasorelaxation in patients with coronary ar tery disease (CAD). In the first study, the relationship between plasma lev els of oxidized LDL and LDL cholesterol were investigated in 88 patients wi th CAD. In the second study, the changes in the diameter of the left anteri or descending (LAD) and the left circumflex (LCX) coronary arteries were me asured after intracoronary administration of acetylcholine (15 mug) and iso sorbide dinitrate (2.5 mg) in 15 patients with CAD. Plasma oxidized LDL lev els were determined with a sandwich enzyme-linked immunosorbent assay. Plas ma oxidized LDL levels did not correlate with plasma LDL cholesterol levels (r=-0.03, p=NS), The % diameter changes (mean+/-SEM) in the LAD and LCX af ter intracoronary acetylcholine were -8.3+/-3.5% and -10+/-4.2%, respective ly. The % diameter changes in the LAD and LCX after intracoronary isosorbid e dinitrate were 23+/-4.8% and 23+/-5.1%, respectively. The % diameter chan ges in the LAD and LCX inversely correlated with plasma oxidized LDL levels after intracoronary acetylcholine (LAD: r=-0.55, p=0.03; LCX: r-0.59, p=0. 02), but were not after intracoronary isosorbide dinitrate. Plasma LDL chol esterol, triglyceride, and high-density lipoprotein cholesterol levels did not correlate with the coronary vasoreaction to acetylcholine. In conclusio n, plasma oxidized LDL levels do not correlate with plasma LDL-cholesterol levels and are related to impairment of endothelium-dependent coronary vaso dilation in patients with CAD.