Coronary calcium (CAC): when a scan changes the plan

If you're in that "in‑between" risk zone—where you're trying to decide how aggressive to be—coronary artery calcium (CAC) is one of the most useful tools we have.

CAC is not perfect, but it can be a powerful way to answer a real-life question:

"Do I have evidence of plaque—and how urgent is prevention for me?"

TL;DR

• CAC is a low-dose CT that measures calcified plaque in the coronary arteries.
• It helps most when risk is uncertain (not clearly low or clearly high).
• A CAC of 0 often lowers near-term risk (not always—context matters).
• Higher CAC (especially 100+) usually supports more intensive prevention.
• CAC doesn't replace lifestyle. It helps match treatment intensity to your actual plaque burden.

What CAC measures (and what it doesn't)

CAC measures calcified plaque. It does not detect all plaque (soft plaque can exist), but calcium is a strong marker of atherosclerosis.

Think of it as a "plaque footprint."

Who is CAC for?

CAC is most helpful when:

• You're 40+ (sometimes younger with strong family history/metabolic risk)
• You're deciding about statins or intensity of LDL/ApoB lowering
• You have borderline/intermediate risk, or risk enhancers like:
  • family history of early ASCVD
  • metabolic syndrome, diabetes, CKD
  • elevated Lp(a)
  • persistent LDL/ApoB elevation

CAC is usually less helpful if you already have known ASCVD (you're already high-risk) or if you're clearly very low risk.

How do I interpret the score?

A simple way to think about CAC:

• 0: no detectable calcified plaque (often reassuring for near-term risk)
• 1–99: mild plaque (may support moderate-intensity prevention)
• 100–399: moderate plaque (often supports more aggressive therapy)
• 400+: extensive plaque (usually warrants intensive prevention)

Context matters: age, other risk factors, family history, Lp(a), ApoB, etc.

Does CAC = 0 mean I'm safe forever?

Not quite. CAC = 0 is reassuring for near-term risk, but:

• Soft (non-calcified) plaque can still exist
• Risk can change over time (especially with metabolic disease progression)
• Some people with very high Lp(a) or familial hypercholesterolemia may still benefit from aggressive prevention despite CAC = 0

CAC = 0 is a strong negative risk marker, but it's not a lifetime guarantee. Prevention is still important.

Practical next steps

• If you're in the "should I or shouldn't I?" zone for statins or intensity, ask about CAC.
• If CAC is elevated, ask: "What is my ApoB goal?" and "What else can I optimize?"
• If CAC = 0, celebrate—but don't abandon prevention. Lock in the basics: nutrition, movement, sleep, BP, weight trend, glucose.

References (patient-friendly)

• 2018 AHA/ACC Multisociety Cholesterol Guideline (Circulation, 2019)
• 2019 ACC/AHA Guideline on Primary Prevention (Circulation, 2019)
• Multi-Ethnic Study of Atherosclerosis (MESA) CAC data (various publications)

Educational content only; not medical advice.