VAP Cholesterol Test Identifies Treatment Effects Of Combination Therapy
Using the VAP Cholesterol Test from Atherotech, Inc., investigators led by Michel Farnier M.D., of Point Medical, Rond Point de la Nation, Dijon, France, have reported beneficial changes in lipoprotein subclasses and LDL particle size using combination therapy. The information could be helpful to physicians because of the known association between abnormal lipoprotein subfractions and increased cardiovascular risk in patients with mixed hyperlipidemia.
Using the Vertical Auto Profile (VAP Test) and S3GGE particle methods, researchers from the recent study titled VAP II analysis of lipoprotein subclasses in mixed hyperlipidemic patients on treatment with ezetimibe/simvastatin and fenofibrate discovered that combination therapy achieved greater reductions in cholesterol classes in high-risk patients and resulted in greater positive changes in lipoprotein profile than monotherapy.
Because of the complex nature of mixed hyperlipidemia, medical guidelines recommend treating patients with a combination of lipid-lowering agents. However, clinicians continue to search for the optimal combination to achieve target lipid levels.
"Mixed hyperlipidemia is characterized by an excess of small, dense LDL associated with an increase of triglyceride and a decrease of HDL-cholesterol levels," said Farnier, lead author of the study. "The patients with mixed dyslipidemia frequently require a combination therapy to normalize this atherogenic lipoprotein profile, and in this specific study the combined therapy of ezetimibe/simvastatin and fenofibrate has produced favorable effects on all the atherogenic lipoprotein subclasses."
Details of the 12-week, multi-center, double blind, parallel group study were published in the Journal of Lipid Research. In the study, 611 patients with mixed hyperlipidemia were randomized to one of four treatment groups: placebo; ezetimibe/simvastatin (10/20 mg/d); fenofibrate (160 mg/d); or ezetimibe/simvastatin (10/20 mg/d) + fenofibrate (160 mg/d) for 12 weeks. The primary efficacy endpoint of the trial was percent change in LDL-C from baseline to study endpoint after treatment with ezetimibe/simvastatin + fenofibrate versus fenofibrate alone.
Detailed evaluation of the effects of ezetimibe/simvastatin and fenofibrate both as monotherapy and in coadministration was achieved by examining their effects on individual lipoprotein subclasses. Cholesterol associated with very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), LDL and HDL subfractions was quantified using the Vertical Auto Profile method. LDL particle size was determined using segmented gradient gel electrophoresis (S3GGE Berkeley Heart Lab).
A key feature of the comprehensive VAP Test is the identification of the major lipid components of residual risk leading to proper individualized therapy. The VAP Test provides researchers and medical professionals with direct measurement of LDL, HDL and all relevant subclasses, and includes non-HDL, a highly accurate determination of apoB, and emerging risk factors such as Lp(a), remnants and small dense LDL.
"We're pleased that the VAP Test was essential in helping investigators identify an optimal combination of therapies for the treatment of mixed hyperlipidemia," said James Ehrlich, M.D., Atherotech's chief medical officer. "Examining in detail the effect of these therapies on lipoprotein subclasses should lead to improved treatment of at-risk individuals exhibiting elevated LDL, triglycerides and non-high density lipoprotein (HDL) cholesterol plus low HDL."
Researchers reported that ezetimibe/simvastatin and fenofibrate, both as separate therapy and in coadministration, produced beneficial changes in the distribution of lipoprotein subclasses within the VLDL to LDL density range. The combination of ezetimibe/simvastatin + fenofibrate produced greater reductions in VLDL, IDL, and LDL (relative to other treatment groups) and greater improvements in the distribution of LDL subfractions with a shift from smaller, more dense to larger, more buoyant LDL particle size in patients with mixed hyperlipidemia.
Eligible patients for the study were men and women aged 18 to 79 years with mixed hyperlipidemia and no coronary heart disease (CHD), CHD-equivalent disease (except for Type 2 diabetes), or CHD risk score >20% as defined by NCEP ATP III.