LDL-C or apoB as the Best Target for Reducing Coronary Heart Disease

Should Apob be Implemented into Clinical Practice?

Helena Vaverkova

Disclosures

Clin Lipidology. 2011;6(1):35-48. 

In This Article

In which Populations does LDL-C most Underestimate the Number of Atherogenic Particles?

LDL-C most underestimates the number of atherogenic lipoprotein particles in conditions with a large prevalence of sdLDL. It was proved that sdLDL starts to increase with TG levels of greater than or equal to 133 mg/dl (1.5 mmol/l).[39] The increased number of sdLDL is very common in subjects with visceral obesity, metabolic syndrome[40,41] and diabetes mellitus.[8]

Data from the Framingham Heart Study (FHS) participants demonstrate a significant increase in apoB levels (p < 0.0001 for trend) and LDL particle concentration as assessed by the NMR method (p < 0.0001 for trend) with an increasing number of components of the metabolic syndrome, while there was no change in LDL-C levels in those with one to five symptoms.[40] Concordance of LDL particles with apoB levels and discordance of both of these parameters with LDL-C further supports the view that apoB is a good marker of LDL particle numbers.

Han et al. compared the association of LDL-C, non-HDL-C and apoB with components of metabolic syndrome in Korean subjects.[41] LDL-C had little if any correlation to components of metabolic syndrome. Only apoB had a significant odds ratio for metabolic syndrome after mutual adjustment for non-HDL-C.

In T2D, the most common dyslipidemia is hypertriglyceridemic hyper-apoB, which is associated with the presence of small LDL particles.[8] Thus, T2D is another condition in which LDL-C underestimates the true number of atherogenic particles.

It is well known that diabetes increases the risk of CVD more in women than in men. In particular, women who become diabetic differ from nondiabetic women in their markedly increased concentrations of apoB, while their LDL-C and non-HDL-C remain comparable with nondiabetic women.[42]

Familial combined hyperlipidemia (FCH) also belongs to clinical entities associated with insulin resistance, an increased number of sdLDL and disproportionately increased concentration of apoB compared with LDL-C.[43] Diagnosis of this most common familial dyslipidemia is based on measuring apoB and not just lipids.[44] FCH is found in approximately 0.5–2% of the general population and in 10–20% of patients with premature MI. In some cohorts of patients with a history of MI without age limits, FCH was found in up to 40% of cases.

Small dense LDL is also frequently found in patients with CVD,[16] especially in those with relatively low total cholesterol and LDL-C. In elderly people, LDL-C loses its predictive power while apoB still predicts the CHD risk.[24] Approximately 45% of the population over 60 years of age have metabolic syndrome, which is characterized by an increased number of LDL particles at a relatively normal LDL-C concentration.[40]

Thus, apoB measurement in order to assess CHD risk is especially important in the rapidly growing subset of the population with obesity, characteristics of metabolic syndrome, diabetes and in a growing subset of the older population.

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