Shear stress-dependent platelet function after LDL cholesterol apheresis.

Background: Platelets play a crucial role in the pathogenesis of acute coronary syndrome (ACS). Thrombus formation with subsequent arterial occlusion is a major determinant in ACS and stroke. Platelets also essentially contribute to the development and progression of atherosclerotic lesions. The aim of the present study was to investigate the effects lipid lowering by LDL apheresis on platelet function in patients with coronary artery disease.

Methods: In six patients with angiographically proven coronary artery disease, venous blood samples were obtained before and after LDL cholesterol apheresis. Citrated whole blood (200 microl) was circulated in polystyrene wells at a shear rate of 1875 s(-1) for 2 min with a rotating teflon cone. Shear-stress dependent platelet adhesion was measured before and after apheresis.

Results: After apheresis, there were significant reductions in LDL (-58%) and HDL (-17%) cholesterol, triglycerides (-43%), fibrinogen (-52%), lipoprotein (a) (-57%) and CRP (-57%) levels. LDL apheresis significantly reduced shear-stress dependent platelet adhesion. Bolus administration of heparin significantly prolonged activated clotting time, but had no significant effect on platelet adhesion or aggregates.

Conclusions: In patients with coronary artery disease, shear-stress dependent platelet adhesion is reduced by a single LDL apheresis. In addition to its cholesterol-lowering effect, LDL apheresis reduces circulating levels of fibrinogen and C-reactive protein.