Coronary Artery Calcium Scoring — Indication, Interpretation & LLT Modification (2026)

Use CAC scoring to reclassify primary-prevention patients when the PREVENT-ASCVD score leaves clinical uncertainty. CAC results then modify LDL and non-HDL treatment goals, not just the decision to treat.

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Step 1 — Confirm the patient is a CAC candidate

Class 1 indication:

• Men ≥40 years OR women ≥45 years
• Borderline (3–<5%) OR intermediate (5–<10%) 10-year PREVENT-ASCVD risk
• Clinical uncertainty about whether to initiate lipid-lowering therapy
• No existing ASCVD, no automatic Class-1 LLT indication (otherwise CAC does not change the "whether" decision)

CAC has no clear role in:

• High (≥10%) 10-year ASCVD risk — proceed to high-intensity statin regardless; CAC should not be used to defer LLT in this group
• Low (<3%) 10-year risk WITHOUT other high-risk features — CAC rarely changes management
• Severe hypercholesterolaemia (LDL ≥190 mg/dL) or clinical/genetic FH — treat regardless; CAC may still inform intensity but not initiation
• Diabetes with multiple ASCVD risk factors or long-standing poorly-controlled DM — automatic high-intensity statin
• Patients <40 years (men) or <45 years (women) — CAC yield is low; the test under-identifies early non-calcified plaque

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Step 2 — Order the CAC scan

• Non-contrast, gated chest CT of the heart
• Low radiation dose (~1 mSv, lower than mammography)
• Results reported in Agatston Units (AU) AND age/sex-matched percentile
• No fasting, no contrast, no beta-blockade needed in most centres

Consider patient-level issues before ordering:

• Incidental findings on the scan (lung nodules, aortic dilation) may prompt further tests — brief the patient
• Radiation is small but not zero; avoid routine repeated scans more often than every 3–7 years
• Cost / insurance coverage varies widely
• Patient anxiety about either a positive or a zero result — set expectations in advance

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Step 3 — Interpret the CAC score and modify LDL / non-HDL goals

CAC score (Agatston Units)	Risk reclassification	LDL-C goal	Non-HDL-C goal	Statin
0 AU (with no other high-risk features)	Low — can defer LLT; repeat CAC in 3–7 years	—	—	Lifestyle
0 AU with FH / LDL ≥190 / DM / age >40 + smoker / strong family history premature ASCVD	Treat regardless (CAC = 0 is NOT reassuring in these groups)	Per baseline risk / FH criteria	Per baseline risk	Moderate-to-high
1–99 AU OR <75th percentile	Reclassify toward LLT (Class 2a)	<100 mg/dL (≥30% reduction)	<130 mg/dL	Moderate-intensity
100–299 AU OR ≥75th percentile OR moderate-to-severe incidental CAC on non-cardiac CT	Reclassify toward LLT (Class 1)	<70 mg/dL (≥50% reduction)	<100 mg/dL	Moderate-to-high
≥300 AU	High-risk — treat as such	<70 mg/dL (≥50% reduction)	<100 mg/dL	High-intensity
≥1000 AU	Very-high-risk — aggressive goals (Class 1)	<55 mg/dL	<85 mg/dL	High-intensity + consider non-statin add-on

ApoB goals once LDL-C and non-HDL-C targets are met (Class 2 for ApoB measurement in LLT recipients with diabetes / CKM syndrome / TG ≥200):

LDL-C goal	ApoB goal
<100 mg/dL	<90 mg/dL
<70 mg/dL	<70 mg/dL
<55 mg/dL	<55 mg/dL

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Step 4 — Decide repeat CAC timing

• CAC = 0 and deferring LLT → repeat in 3–7 years to detect calcium development
• CAC >0 and on LLT → routine repeat CAC is NOT recommended; statins stabilise plaque but may paradoxically increase calcium density. Serial CAC on-statin is not a treatment-monitoring tool
• Progression of CAC is itself a risk signal if measured, but monitoring with repeat CAC in treated patients is not current standard

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Step 5 — Use CAC thoughtfully in special scenarios

Incidental CAC on a non-cardiac CT (e.g. chest CT for other indications)

• A non-gated chest CT showing CAC is a legitimate signal
• Qualitative grading (none / mild / moderate / severe) is clinically useful
• Moderate-to-severe incidental CAC → treat as CAC 100–299 or ≥300 per the above table
• Absence of CAC on a non-gated scan does NOT equate to a CAC score of 0 (high false-negative rate due to non-gated acquisition) — do a dedicated CAC scan if the "zero" needs to be clinically relied on

CT coronary angiography (CCTA)

• Class 2b recommendation to inform risk assessment in individuals with high burden of non-calcified plaque (patients with HIV, inflammatory disorders, diabetes)
• Not a first-line tool for routine primary prevention risk assessment
• Guideline does NOT address downstream ischaemic testing based on CAC
• The National Lipid Association specifically recommends AGAINST using CAC alone to test for obstructive CAD or ischaemia

Smokers

• Current cigarette smoking changes the calculus — CAC = 0 in a smoker is less reassuring than in a non-smoker; shared decision still leans toward LLT

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Guardrails

• CAC = 0 is reassuring but NOT a license to ignore risk — repeat in 3–7 years, and treat regardless if FH / LDL ≥190 / DM / strong family history / smoker
• CAC in a high-risk patient does not help the decision — do not use CAC to try to DE-escalate treatment in a patient already classified as high-risk by PREVENT or by automatic Class-1 criteria
• Incidental non-gated CAC underestimates true CAC — a "no CAC" report from a non-gated CT is not equivalent to a formal CAC = 0 scan
• CAC does not test for ischaemia — a high CAC does not mandate stress testing; a low CAC does not exclude an acute coronary event
• Do NOT repeat CAC yearly or every 2 years — biologically CAC changes slowly in treated patients and repeated radiation adds up over a lifetime
• ApoB goals should drive final intensification in patients with diabetes, CKM syndrome, or TG ≥200 even after LDL-C and non-HDL-C targets are met
• Discuss cost and incidental findings before ordering — a positive scan may lead to downstream testing the patient is not expecting
• CAC = 0 under age 40 is uninformative — early plaque is often non-calcified; waiting until the Class-1 age window (men ≥40, women ≥45) improves yield
• Do not use CAC to replace a conversation — it is a reclassification tool, not a decision-making substitute

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Related MD2SKILL skills

• prevent-ascvd-risk-calculator-interpretation — the Step-1 risk calculation that defines the CAC indication
• dyslipidemia-cpr-framework-2026 — the full CPR framework (CAC is the "R" step)
• dyslipidemia-ldl-treatment-goals-2026 — the LDL and non-HDL goals that CAC modifies

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Sources

Primary: 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Multisociety Guideline on the Management of Dyslipidaemia.

Review used for extraction: Abramov D et al. Primary Prevention of Dyslipidemia: 10 Practice-Changing Takeaways from the 2026 ACC/AHA Multisociety Guideline. Current Atherosclerosis Reports. 2026;28:63. DOI: 10.1007/s11883-026-01437-9. Section "Key Message 5: Additional Risk Stratification — Coronary Artery Calcium" and Table 1.