Coronary Calcium Risk Calculator (MESA Model)

How Coronary Artery Calcium Modifies Cardiovascular Risk

The coronary artery calcium (CAC) score quantifies calcified atherosclerotic plaque in the coronary arteries using non-contrast cardiac CT. CAC is one of the strongest imaging predictors of future coronary events, with a graded relationship between calcium burden and cardiovascular risk.

The MESA CAC risk calculator combines the CAC score with traditional cardiovascular risk factors to estimate an individual's 10-year risk of coronary heart disease (CHD). In the Multi-Ethnic Study of Atherosclerosis, adding CAC to traditional risk factors improved discrimination (C-statistic 0.80 versus 0.75) and reclassified a substantial proportion of intermediate-risk individuals into higher- or lower-risk groups. The 2026 ACC/AHA Guideline on the Management of Dyslipidemia reinforces the role of CAC scoring in guiding lipid-lowering therapy.

2026 CAC-Based Treatment Recommendations

The 2026 ACC/AHA guideline provides treatment guidance based on CAC score in adults without established ASCVD:

• CAC = 0: Reasonable to defer statin therapy and reassess with repeat CAC in 3–7 years, provided no higher-risk conditions are present (such as familial hypercholesterolaemia, diabetes, smoking, or strong family history of premature ASCVD).
• CAC 1–99 and <75th percentile: Moderate-intensity statin therapy is reasonable, typically targeting ≥30–49% LDL-C reduction.
• CAC ≥100 or ≥75th percentile: Statin therapy is recommended, generally aiming for LDL-C <1.8 mmol/L and non–HDL-C <2.6 mmol/L.
• CAC ≥300: Indicates high atherosclerotic burden. Aggressive lipid-lowering therapy is recommended, often targeting ≥50% LDL-C reduction, with consideration of additional agents if needed.
• CAC ≥1000: Very high atherosclerotic burden. Event rates approach those seen in secondary prevention, and intensive lipid-lowering therapy is usually warranted.

When CAC Scoring Is Helpful

The 2026 guideline supports CAC scoring as part of a stepwise approach to risk assessment: calculate risk with the PREVENT equations, personalise with risk-enhancing factors, then reclassify with selective CAC scoring when uncertainty remains. CAC testing is particularly helpful in:

• Adults at intermediate (5–<10%) or selected borderline (3–<5%) PREVENT risk where statin decisions are uncertain
• Individuals seeking more precise risk assessment before committing to long-term medication
• Younger adults with a strong family history of premature cardiovascular disease
• Patients with elevated lipoprotein(a) or other risk-enhancing factors

Incidental CAC detected on non-cardiac CT should also be considered when assessing cardiovascular risk.

Situations Where CAC Scoring Is Less Helpful

• Patients with established cardiovascular disease, where treatment decisions are already clear
• Patients with familial hypercholesterolaemia, where CAC = 0 should not be used to defer statin therapy
• Individuals already on statin therapy, since statins may increase measured CAC while stabilising plaque
• Very young adults (<40 years), where non-calcified plaque may be present despite a CAC of zero

For further detail, see our guide to coronary artery calcium scoring.

Interpreting CAC Scores

• CAC = 0 — no detectable coronary calcium; very low short-term risk
• CAC 1–9 — minimal plaque
• CAC 10–99 — mild plaque burden
• CAC 100–299 — moderate atherosclerosis
• CAC 300–999 — severe atherosclerosis; event rates approach those of treated ASCVD patients
• CAC ≥1000 — extensive atherosclerosis; event rates approach secondary prevention populations

Risk should always be interpreted in clinical context, including age and sex percentile, symptoms, other risk factors, and family history.