Effects of increasing doses of simvastatin on fasting lipoprotein subfractions, and the effect of high-dose simvastatin on postprandial chylomicron remnant clearance in normotriglyceridemic patients with premature coronary sclerosis

Postprandial hyperlipidemia has been linked to premature coronary artery disease (CAD) in fasting normotriglyceridemic patients. We investigated the effects of increasing doses of simvastatin up to 80 mg/day on fasting and postprandial lipoprotein metabolism in 18 normotriglyceridemic patients with premature CAD. Fasting lipoprotein subfractions and cholesteryl ester transfer protein (CETP) activity were determined after each 5-week dose titration (0, 20, 40 and 80 mg/day). At baseline and after treatment with simvastatin 80 mg/day, standardised Vitamin A oral fat loading tests (50 g/m2; 10 h) were carried out. Ten normolipidemic healthy control subjects matched for gender, age and BMI underwent tests without medication. Treatment with simvastatin resulted in dose-dependent reductions of fasting LDL-cholesterol, without changing cholesterol levels in the VLDL-1, VLDL-2 and IDL fractions. In addition, simvastatin decreased CETP activity dose-dependently, although HDL-cholesterol remained unchanged. Simvastatin 80 mg/day decreased fasting plasma triglycerides (TG) by 26% (P< 0.05), but did not decrease significantly TG levels in any of the subfractions. The TG/cholesterol ratio increased in all subfractions. The plasma TG response to the oral fat loading test, estimated as area under the curve (TG-AUC), improved by 30% (from 21.5 ± 2.5 to 15.1 ± 1.9 mmol h/L; P< 0.01). Treatment with simvastatin 80 mg/day improved chylomicron remnant clearance (RE-AUC) by 36% from 30.0 ± 2.6 to 19.2 ± 3.3 mg h/L (P< 0.01). After therapy, remnant clearance in patients was similar to controls (19.2 ± 3.3 and 20.3 ± 2.7 mg h/L, respectively), suggesting a normalization of this potentially atherogenic process. In conclusion, high-dose simvastatin has beneficial effects in normotriglyceridemic patients with premature CAD, due to improved chylomicron remnant clearance, besides effective lowering of LDL-cholesterol. In addition, the lipoprotein subfractions became more cholesterol-poor, as reflected by the increased TG/cholesterol ratio, which potentially makes them less atherogenic.