What is Apo B? And did you know it is a lipid marker unaffected by fasting?

ApoB directly quantifies the number of atherogenic lipoproteins, providing a more accurate measure of atherogenic particle burden than LDL-C, which reflects the cholesterol mass carried by LDL particles.

ApoB measurement enhances the accuracy of ASCVD risk assessment in untreated populations by directly assessing the number of atherogenic particles, including LDL, VLDL, and Lp(a). ApoB provides a more direct marker of lipoprotein particle number, bypassing the variability introduced by lipoprotein composition. Integrating apoB into routine risk stratification has been supported by large cohort studies and meta-analyses, which consistently demonstrate its superior predictive value compared with traditional lipid markers.

ApoB measurement is standardized and unaffected by fasting status. By incorporating apoB measurement in persons with hypertriglyceridemia or diabetes, clinicians may better identify high-risk individuals who may otherwise be overlooked by traditional metrics, enabling the timely initiation of LLTs. ApoB can also aid in the identification and characterization of lipid phenotypes, such as atherogenic dyslipidemia and inherited lipid disorders.

This distinction is clinically relevant in populations with CKM (Cardiovascular-Kidney-Metabolic syndrome), in which cholesterol-depleted LDL particles are common.1 In such settings, particularly in individuals with established ASCVD, CKM syndrome, diabetes, and/or elevated TG, discordance between LDL-C and apoB may be observed. LDL-C may appear at goal while apoB remains elevated, masking residual risk and possibly leading to undertreatment. Observational studies and post hoc analyses from randomized trials demonstrate that apoB is more strongly associated with cardiovascular events than LDL-C or non–HDL-C when the Friedewald equation is used to estimate LDL-C.1–4 These findings highlight the utility of apoB in identifying individuals who may benefit from therapeutic intensification, even after apparent LDL-C goal attainment. The Martin/Hopkins method to estimate LDL-C markedly reduces discordance with apoB compared with the Friedewald equation. Among individuals with LDL-C <70 mg/dL (1.8 mmol/L) or <100 mg/dL (2.6 mmol/L) by Martin/Hopkins, only ∼2% and ∼1% of individuals had non–HDL-C and apoB levels exceeding guideline targets.15,16 Measurement of apoB can support decisions regarding nonstatin therapies, such as ezetimibe, bempedoic acid, proprotein convertase subtilisin/kexin type 9 (PCSK9) monoclonal antibodies (mAb), or inclisiran.

From: https://www.ahajournals.org/doi/10.1161/CIR.0000000000001423#sec-7-3