Why LDL-C Is Not Enough

LDL cholesterol (LDL-C) measures the total amount of cholesterol carried in LDL particles — but it does not count the number of particles. Two people can have identical LDL-C values but very different particle counts, and particle count is what drives atherogenesis.

ApoB (Apolipoprotein B) solves this problem. Every atherogenic lipoprotein particle — LDL, VLDL, IDL, and Lp(a) — carries exactly one ApoB molecule. ApoB is therefore a direct count of the particles that can penetrate arterial walls and initiate plaque formation.

Understanding ApoB

ApoB is now considered by many cardiovascular researchers to be the most important modifiable cardiovascular risk marker. An ApoB above 90 mg/dL is generally considered elevated; below 60 mg/dL is the target for high-risk individuals.

ApoB is widely available and inexpensive. It is not included in standard lipid panels but can be added to most lab orders. If you have only ever had a standard lipid panel, you have an incomplete picture of your cardiovascular risk.

Lp(a) — The Genetic Risk Factor

Lipoprotein(a) is a modified form of LDL with an additional protein attached. It is largely genetically determined and does not change meaningfully with diet or lifestyle. Elevated Lp(a) is an independent cardiovascular risk factor — meaning it adds risk on top of whatever your ApoB or LDL-C shows.

Lp(a) should be tested at least once in every adult. If elevated (above 50 mg/dL or 125 nmol/L), it changes risk stratification and may influence treatment decisions. Emerging pharmacological interventions specifically targeting Lp(a) are in late-stage clinical trials.

CAC Scan — Quantifying Plaque

A Coronary Artery Calcium (CAC) scan is a low-dose CT scan that measures calcified plaque in the coronary arteries. It provides a direct, structural measure of atherosclerosis — not a prediction, but a measurement of what has already accumulated.

A CAC score of 0 is highly reassuring and associated with very low near-term cardiovascular event risk. A score above 100 significantly changes risk stratification and often influences treatment decisions including statin therapy, aspirin, and lifestyle interventions.

• CAC = 0: Very low near-term risk. Retest in 3–5 years.
• CAC 1–99: Mild plaque. Lifestyle optimization is the priority.
• CAC 100–399: Moderate risk. Discuss pharmacotherapy with your physician.
• CAC ≥400: High risk. Aggressive intervention warranted.

Carotid Ultrasound (CIMT)

Carotid Intima-Media Thickness (CIMT) measures the thickness of the inner two layers of the carotid artery wall using ultrasound. It is non-invasive, involves no radiation, and can detect early atherosclerosis before it becomes symptomatic.

CIMT is particularly useful for younger individuals where CAC may still be zero but early arterial changes are developing. It can also detect soft plaque that CAC scanning misses.

The Role of Insulin Resistance

Insulin resistance is a major driver of cardiovascular risk — through multiple mechanisms including elevated triglycerides, reduced HDL, increased small dense LDL particles, endothelial dysfunction, and systemic inflammation.

Addressing insulin resistance is therefore not just a metabolic health intervention — it is a cardiovascular intervention. The two domains are deeply interconnected.