Low density lipoprotein size in relation to carotid intima-media thickness in coronary artery disease.

Objective: With increasing interest in the role of non-traditional lipid risk factors in coronary artery disease, we undertook this study to relate LDL subclass size and carotid intima-media thickness of the common carotid artery in coronary artery disease patients.
Methods: The study was conducted in 106 patients during their first visit (study group I) and after 12 months (study group II). Intima-media thickness of the common carotid artery was determined using B-mode ultrasound. Separation of LDL subclasses was preformed by 3-31 % polyacrylamide gradient gel electrophoresis.
Results: LDL3 was the dominant subclass in both study groups, but there was statistically significant difference in the distribution of dominant LDL subclasses (p<0.01). The mean carotid intima- media thickness was significantly increased (p<0.001) in coronary artery disease patients after 12 months period. There was significant negative correlation between intima-media thickness and LDL size in both study groups (p<0.05). Intima-media thickness was not significantly correlated with plasma lipid concentrations. Multiple regression analyses show that strongest independent predictor of the intima-media thickness variation was diastolic blood pressure, followed by LDL size and age, and accounted for 29 % of the observed variability in intima-media thickness.
Conclusion: LDL particle size is independently associated with carotid intima-media thickness in coronary artery disease patients with normal levels of traditional lipid risk. These results imply that small, dense LDL subclasses are an important indicator for assessing atherosclerosis and its progression (Tab. 4, Ref. 39).