LDL particle size in relation to intima-media thickness and plaque occurrence in the carotid and femoral arteries in patients with hypercholesterolaemia

Objectives. Small LDL particle size has been shown to be associated with co ronary artery disease. However, no previous study has been performed relati ng LDL particle size to ultrasound measurement of atherosclerosis in hyperc holesterolaemic subjects. The main aims of the present study were therefore : (i) to investigate the relationship between intima-media thickness (IMT) of the carotid bulb and LDL particle size in patients with primary hypercho lesterolaemia (n = 102) and in matched normocholesterolaemic controls (n = 102); and (ii) to investigate the relationship between plaque occurrence in the carotid and femoral arteries and LDL particle size. LDL particle size was determined by subjecting serum to 2-16% polyacrylamide gradient gel ele ctrophoresis. Results. The results showed that patients with primary hypercholesterolaemi a had smaller LDL peak particle size compared with healthy control subjects (P < 0.001 for men, P = 0.006 for women). However, the difference in LDL p eak particle size between patients with hypercholesterolaemia and controls disappeared when adjusting for serum triglycerides. There was no associatio n between increasing IMT of the carotid bulb and decreasing LDL peak partic le size or between the occurrence of moderate to large plaques in the carot id and femoral arteries and small LDL peak particle size. However, metaboli c variables such as serum triglycerides, HDL, blood glucose, body mass inde x, and also systolic blood pressure were associated with LDL peak particle size. Conclusion. The lack of an association between atherosclerosis, as measured by ultrasound, and small LDL particle size in patients with hypercholester olaemia implies that other risk factors, such as hypercholesterolaemia and high blood pressure, may overshadow any importance of small LDL particle si ze.