03 May 2026 5 min read

The Definitive Guide to Coronary Artery Calcium Scoring

A coronary artery calcium score of zero in a 50-year-old carries a 10-year cardiovascular event rate below 1 percent, regardless of traditional risk factors (Blaha et al., 2016). A score above 300 in the same person raises that rate above 10 percent. The test takes 10 minutes, requires no contrast dye, no IV, and costs between $75 and $150 out of pocket. It is a low-dose CT scan of the heart that quantifies calcified atherosclerotic plaque in the coronary arteries, and it provides more prognostic information about your cardiovascular future than any combination of cholesterol numbers, blood pressure readings, or risk calculators.

The Multi-Ethnic Study of Atherosclerosis (MESA), which followed 6,814 adults without known cardiovascular disease for over 15 years, demonstrated that the CAC score reclassified risk in 30 to 50 percent of individuals who were in the intermediate risk category by traditional models (Detrano et al., 2008). People told they were at moderate risk were either far safer or far more endangered than their cholesterol panel suggested. The CAC scan resolved the ambiguity.

Heart disease kills more people than every cancer combined. The majority of first heart attacks occur in people who were never told they were at high risk. The CAC score is the closest thing to a direct look at the disease itself.

Key Takeaways

A CAC score of zero is the strongest negative predictor of cardiovascular events over the next decade.
The test reclassifies 30 to 50% of intermediate risk individuals into high or low risk.
The scan costs $75 to $150, takes 10 minutes, and requires no contrast or preparation.
A rising CAC score over time is more informative than a single measurement.

What a CAC Score Actually Is

A coronary artery calcium score is a quantification of calcified plaque in the coronary arteries, measured by non-contrast cardiac CT and reported as an Agatston score. Most people think a clean cholesterol panel means clean arteries. It does not. LDL is a risk factor for atherosclerosis, not a measurement of atherosclerosis. The CAC score measures the disease directly. An Agatston score of zero means no detectable calcified plaque. A score of 1 to 99 indicates mild plaque. A score of 100 to 399 is moderate. Above 400 is extensive disease.

The Problem with Risk Factors Alone

Standard cardiovascular risk assessment uses inputs like age, sex, LDL cholesterol, HDL cholesterol, blood pressure, smoking status, and diabetes status. These models are population-level tools. They work on averages. They do not work on individuals.

A 48-year-old man with an LDL of 130 mg/dL, blood pressure of 128/82, no diabetes, and no smoking history receives a 10-year ASCVD risk of approximately 5 to 7 percent. A CAC scan resolves the equivocation. If the score is zero, the risk is below 1 percent. If the score is 250, the disease is already present and treatment should begin immediately.

The Truth: What MESA and Other Cohorts Show

The Multi-Ethnic Study of Atherosclerosis followed 6,814 adults aged 45 to 84. CAC scoring independently predicted coronary events and added prognostic value beyond all traditional risk factors combined (Detrano et al., 2008). The hazard ratio for a CAC score above 300 versus zero was 6.84 for coronary events.

Blaha et al. (2016) demonstrated that a CAC score of zero conferred a 10-year major adverse cardiovascular event rate below 1 percent across all age, sex, and ethnic subgroups.

Serial CAC scoring shows that the rate of CAC progression is an independent predictor of events, beyond the absolute score (Budoff et al., 2013).

The Most Common Mistake

The biggest error is getting a CAC scan and then doing nothing with the result. A score of zero is powerful but not permanent. Soft plaque, which is non-calcified and potentially more dangerous in the short term, is not detected by this scan. Conversely, a high score demands action, not just awareness.

Signals to Watch

Signal	Lab Normal	Optimal Target
CAC score (Agatston)	0	0 (maintain)
LDL-C	< 100 mg/dL	< 70 mg/dL if CAC > 0
ApoB	< 130 mg/dL	< 80 mg/dL
Lp(a)	< 50 nmol/L	Genetically determined; know your number
hsCRP	< 3.0 mg/L	< 1.0 mg/L

What To Do

Get a CAC scan if you are over 40 and have any cardiovascular risk factor. The scan is fast, low-radiation (approximately 1 mSv), and requires no preparation.
If your CAC is zero, schedule a repeat in 5 years. A zero score warrants continued lifestyle optimization but does not warrant aggressive pharmacotherapy in most cases.
If your CAC is above 100, start or intensify statin therapy. LDL targets should shift to below 70 mg/dL. ApoB below 80 mg/dL. Blood pressure below 130/80.
Test Lp(a) once in your lifetime. Lipoprotein(a) is genetically determined and not affected by lifestyle. Elevated Lp(a) amplifies cardiovascular risk disproportionately.
Track CAC progression if your baseline is above zero. Repeat scanning at 3 to 5 year intervals. Stable or slowly progressing scores are the target.

How Rewind Fits

This is exactly the kind of structural risk assessment Rewind integrates into your longitudinal health picture. We track ApoB, Lp(a), hsCRP, and lipid subfractions alongside your CAC history.

Start Here

A CAC scan takes 10 minutes and costs less than a dinner out. Start your Rewind membership.

FAQ

What is a good CAC score?

A CAC score of zero is ideal. Scores of 1 to 99 indicate mild plaque. Above 100 warrants medical discussion and likely pharmacotherapy.

How often should you get a CAC scan?

If your initial score is zero, repeat in 5 to 10 years. If above zero, repeat in 3 to 5 years to track progression.

Does a CAC score of zero mean no heart disease risk?

No. A zero score means no calcified plaque, but soft plaque is not detected. A zero score dramatically lowers but does not eliminate risk.

Is the radiation from a CAC scan safe?

The radiation dose is approximately 1 mSv, equivalent to 2 to 3 months of natural background radiation.

Can lifestyle changes lower a CAC score?

CAC scores do not typically decrease because calcified plaque is stable. However, statins and lifestyle interventions can slow or halt progression.

Rewind Insight: Cholesterol is a proxy. Blood pressure is a proxy. The CAC score is not a proxy. It is a direct measurement of coronary artery disease. We include it in the Rewind framework because the best time to find plaque is before it finds you.

The $100 Question

For the cost of a routine blood draw, a CAC scan answers the single most important question in preventive cardiology: is the disease already there? Rewind pairs that answer with the biomarkers that drive progression. Know your number.

Rewind is a membership-based longevity platform. Individual outcomes vary.

This article is for informational purposes only and does not constitute medical advice.

References

Blaha, M. J., et al. (2016). Role of coronary artery calcium score of zero and other negative risk markers. Circulation, 133(9), 849-858.

Budoff, M. J., et al. (2013). Progression of coronary calcium and incident coronary heart disease events. JACC, 61(12), 1231-1239.

Detrano, R., et al. (2008). Coronary calcium as a predictor of coronary events in four racial or ethnic groups. NEJM, 358(13), 1336-1345.

Grundy, S. M., et al. (2019). 2018 AHA/ACC guideline on the management of blood cholesterol. JACC, 73(24), e285-e350.