Cardiovascular
Apolipoprotein B in cardiovascular risk assessment
Aug
Apolipoprotein (apo) B measurement is a recommended alternative to low-density lipoprotein cholesterol (LDL-C)
The 2021 Canadian Cardiovascular Society guideline on dyslipidemia recommends that physicians may use levels of either non-high-density lipoprotein cholesterol (HDL-C) or apo B instead of LDL-C for screening and targets of treatment.1 Non-HDL-C represents total cholesterol minus cholesterol from HDL particles; apo B represents the total number of atherogenic particles, since 1 apo B molecule is found on each LDL, very low–density lipoprotein, intermediate-density lipoprotein and lipoprotein(a) particle.2
Apolipoprotein B accurately predicts cardiovascular risk
Atherosclerosis is more closely associated with the number of apo B–containing lipoprotein particles than with cholesterol concentration. Clinical trials of statins, ezetimibe and inhibitors of proprotein convertase subtilisin/kexin type 9 indicate that levels of apo B more accurately predict risk of coronary heart disease than levels of LDL-C or non-HDL-C.3
The Canadian Cardiovascular Society provides a guideline for using the marker in clinical practice
The 2021 guideline recommends statin treatment for patients with an intermediate Framingham Risk Score (10%–19.9%) and an apo B level greater than 1.05 g/L, in addition to lifestyle modifications.1 For patients with established cardiovascular disease, intensification of lipid-lowering therapy is indicated when thresholds are surpassed (LDL-C > 1.8 mmol/L, non-HDL-C > 2.4 mmol/L or apo B > 0.7 g/L).1
Apolipoprotein B has practical advantages over other measures
Measurement of apo B is inexpensive and reimbursed across Canada, and can be performed by all laboratories. In contrast to both LDL-C and non-HDL-C, which are calculated, apo B is measured directly. Measurement of apo B does not require fasting and is accurate even when triglycerides are elevated or LDL-C is very low because of treatment.4
Some patients with apparently satisfactory levels of low-density lipoprotein cholesterol have high levels of apolipoprotein B
Levels of apo B and LDL-C are discordant in 20% of patients, including those with elevated triglycerides, type 2 diabetes or obesity. In some patients, LDL-C levels can appear satisfactory, but the true level of circulating atherogenic particles is actually high. An elevated apo B level in these patients predicts a higher risk of atherosclerotic cardiovascular disease.5 In such patients, treatment with a lipid-lowering drug should be considered.
Footnotes
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Competing interests: Robert Hegele reports consulting fees from Akcea–Ionis, Amgen, HLS Therapeutics, Pfizer, Novartis, Regeneron and Ultragenyx. No other competing interests were declared.
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This article has been peer reviewed.
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