Abstract 166: Small Dense LDL Cholesterol Is Associated with Risk for Coronary Heart Disease: The Atherosclerosis Risk in Communities (ARIC) Study

Background— Evidence from in vitro studies indicates that small dense LDL (sd-LDL) is more atherogenic than large buoyant LDL. Previously, sd-LDL has been associated with risk for vascular disease. However, the lack of a standardized sd-LDL assay has hampered its clinical application. Objectives— We tested the hypothesis that elevated plasma sd-LDL-cholesterol (sd-LDL-C) level is associated with risk for incident coronary heart disease (CHD) and stroke in the ARIC cohort. Methods— Plasma sd-LDL-C was measured in 11,419 men and women of the biracial ARIC study using a newly developed automated homogeneous assay. A proportional hazards model was used to examine the relationship between sd-LDL-C, vascular risk factors, and risk for CHD events and stroke over a period of ≈10 years. Results— Mean plasma sd-LDL-C was higher in Caucasians than in African Americans (45.2 vs. 37.4 mg/dL, p<0.0001). Plasma sd-LDL-C levels were strongly correlated with an atherogenic lipid profile and were higher in diabetics vs. non-diabetics (49.6 vs. 42.3 mg/dL, p<0.0001, respectively). sd-LDL-C was associated with incident CHD in a basic model as well as a model that included traditional risk factors and hs-CRP with hazard ratios (HRs) of 1.99 (95%CI: 1.68-2.36) and 1.56 (95%CI: 1.26-1.93) for the highest vs. the lowest quartile, respectively (Table). We did not find a significant association of sd-LDL-C with risk for stroke (Table). Conclusions— sd-LDL-C is associated with incident CHD but does not predict risk for stroke in ARIC participants. Further studies will need to determine whether sd-LDL-C will add value beyond traditional risk factors to cardiovascular risk assessment in clinical practice.