The effect of extracorporeal cholesterol removal on the progression of atherosclerosis

High correlation of plasma lipid levels, especially low density lipoprotein (LDL) cholesterol levels, with the risk of coronary heart disease has been clearly indicated by epidemiologic studies. This study was undertaken to use an animal model of nondiet-induced hyperlipidemia in the homozygous Watanabe heritable hyperlipidemic rabbit (WHHL) to evaluate the effect of plasma cholesterol lowering on the progression of atherosclerosis, and to correlate plasma cholesterol levels with the amount of atherosclerotic plaque. Studies were carried out on ten homozygous WHHL rabbits divided into two groups: lipid lowering (treated) and control (nontreated). Lipid lowering was accomplished by thermofiltration (on-line plasma membrane filtration at 39 degrees C for removal of VLDL and LDL). The treated group had a significantly lower mean plasma level of total cholesterol over the course of the study than the nontreated group (293 vs. 655 mg/dl, p = 0.004). The amount of aortic atherosclerotic plaque in the treated group was also significantly lower than that in the control group (16.9 vs. 44.2%, p = 0.003). Microscopically, thickness measurements of the atherosclerotic lesions revealed that the control group had a thicker intima than the treated group. This study convincingly demonstrated the slowing or interdiction of progression of atherosclerotic lesions with lowering of the plasma total cholesterol level by thermofiltration.