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Coronary Artery Calcium (CAC) Score

A non-invasive scan to detect calcified plaque in the arteries of your heart. This guide explains what the score means, who benefits most, and how it helps refine your cardiovascular risk assessment.

Key facts at a glance

Statistics on utility, radiation, and impact.

Predictive Power
A CAC score of 0 is one of the strongest markers for low cardiovascular risk over the next 5-10 years.
High
Prevalence of Calcification
Approximately half of adults aged 45-84 have some detectable coronary calcium (Score > 0).
~50%
Reclassification Rate
CAC testing reclassifies risk for about 1 in 4 people, often changing treatment plans (e.g., starting or stopping statins).
~25%
Radiation Exposure
A low dose of radiation, roughly equivalent to a mammogram or 4 months of natural background radiation.
~1 mSv
Cost
Often an out-of-pocket expense, though prices vary by imaging center.
~$150-$300

Who this is for

  • You are unsure about starting cholesterol medication (statin).
  • You have intermediate risk factors (e.g., family history, borderline lipids) but no symptoms.
  • You want a direct measure of plaque burden rather than just risk probability.

Who this is NOT for

  • You already have known heart disease (stents, bypass, or prior heart attack).
  • You are already on aggressive lipid-lowering therapy (the result likely won't change management).
  • You are pregnant or looking to avoid all radiation exposure.

What is a CAC Scan?

  • It is a specialized CT scan of the chest that takes about 10-15 minutes.
  • No contrast dye is needed (no needles).
  • It specifically looks for calcium deposits in the coronary arteries, which are markers of established atherosclerosis (plaque).
  • The result is a number (Agatston Score) ranging from 0 to over 1,000.

Understanding the Score

  • 0: No calcified plaque detected. Very low risk of events in the next 5-10 years.
  • 1 - 99: Mild plaque burden. Moderate risk. Lifestyle changes recommended.
  • 100 - 399: Moderate plaque burden. High risk. Statin therapy often considered.
  • 400+: Extensive plaque burden. Very high risk. Intensive preventive therapy usually recommended.

Potential Benefits

  • Personalized Risk: Moves beyond "probability" calculators to show actual disease presence.
  • Treatment Decision: Can be the "tie-breaker" for starting medication if you are on the fence.
  • Motivation: Seeing a positive score can be a powerful motivator for lifestyle adherence.

Limitations & Considerations

  • Radiation: Uses a small amount of ionizing radiation.
  • Soft Plaque: A score of 0 does not rule out "soft" (non-calcified) plaque, though it is less common to have significant soft plaque with a 0 score.
  • Not for Symptomatic Patients: If you have chest pain, other tests (like a stress test or angiogram) are usually more appropriate.

References

Guidelines and key studies.

  1. 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease — J Am Coll Cardiol (2019)
    View source — Primary prevention guidelines recommending CAC for uncertain risk decisions
  2. Biles L, et al.. Coronary Artery Calcium Scoring: The Evidence and the Future — Curr Probl Cardiol (2021)
    View source
  3. Yeboah J, et al.. Coronary Artery Calcium Score and Risk of Cardiovascular Events — JAMA (2012)
    View source
  4. Miedema MD, et al.. Use of Coronary Artery Calcium Testing to Guide Aspirin Utilization — Circ Cardiovasc Qual Outcomes (2014)
    View source

Content is educational and not medical advice. For personal recommendations, consult your clinician.

Coronary Artery Calcium (CAC) Score: What You Need to Know