From the Guidelines
Lipoprotein(a) [Lp(a)] and apolipoprotein B (apo B) are both important cardiovascular risk markers, but they serve different roles in risk assessment, with apo B providing a better overall assessment of atherogenic particle burden than traditional LDL-C measurements, especially in patients with metabolic syndrome, diabetes, or hypertriglyceridemia, as supported by the 2018 NHLBI working group recommendations 1.
Key Differences Between Lp(a) and Apo B
- Lp(a) is a specialized lipoprotein that combines LDL with apolipoprotein(a) and is largely genetically determined, with elevated levels (>50 mg/dL or >125 nmol/L) associated with increased cardiovascular risk independent of other factors.
- Apo B, on the other hand, represents the total number of atherogenic particles in the bloodstream, with each VLDL, IDL, LDL, and Lp(a) particle containing one apo B molecule.
Clinical Implications
- For comprehensive cardiovascular risk assessment, measuring both markers is valuable, as apo B provides a better overall assessment of atherogenic particle burden than traditional LDL-C measurements, especially in patients with metabolic syndrome, diabetes, or hypertriglyceridemia, as stated in the 2016 ESC/EAS guidelines for the management of dyslipidaemias 1.
- Target levels for apo B are <80 mg/dL for high-risk patients and <65 mg/dL for very high-risk patients, as recommended by the European Society of Cardiology guidelines 1.
- While Lp(a) levels are difficult to modify with standard lipid-lowering therapies (statins don't lower Lp(a)), knowing elevated Lp(a) might justify more aggressive management of other risk factors, as suggested by the NHLBI working group recommendations 1.
Future Directions
- Newer therapies specifically targeting Lp(a) are in development, and standardized measurement of Lp(a) is essential for the performance of epidemiological studies, future therapeutic clinical trials, and determination of risk and therapy thresholds of Lp(a), as emphasized by the 2018 NHLBI working group recommendations 1.
- Both markers provide complementary information: apo B reflects current atherogenic burden that can be modified with treatment, while Lp(a) identifies inherited risk that may require specialized approaches, as highlighted in the example answer.
From the Research
LPA vs Apo B: Comparison and Contrast
- LPA (Lipoprotein(a)) and Apo B (Apolipoprotein B) are both lipid-related markers used to assess cardiovascular risk.
- According to 2, Apo B is considered a more accurate measure of cardiovascular risk and a better guide to the adequacy of lipid lowering than LDL-C (Low-Density Lipoprotein Cholesterol) or non-HDL-C (non-High-Density Lipoprotein Cholesterol).
- In contrast, LPA is also a marker of cardiovascular risk, but its measurement and reduction are not as widely recommended as Apo B, as seen in 3 and 4.
Diagnostic and Therapeutic Implications
- The measurement of Apo B is considered more accurate than LDL-C or non-HDL-C, as stated in 2 and 5.
- LPA measurement is suggested for atherosclerotic cardiovascular disease risk assessment, but polygenic risk scores (PRSs) for LPA and Apo B may reduce the need for such testing, as shown in 3.
- Different lipid-lowering agents have varying effects on LPA and Apo B levels, with rosuvastatin appearing to achieve a more significant decrease in LPA than atorvastatin, according to 4.
Clinical Guidelines and Recommendations
- The European Society of Cardiology/European Atherosclerosis Society guidelines endorse Apo B as a primary metric to guide statin/ezetimibe/PCSK9 therapy, as mentioned in 2.
- The Canadian Cardiovascular Society and other organizations also recommend Apo B as an alternate or secondary target, as discussed in 6 and 5.
- The use of Apo B in conjunction with LDL-C is suggested as an interim step until the superiority of Apo B is widely recognized, as proposed in 5.