Coronary Artery Calcium Test (CAC)

You've got a patient in the borderline-to-intermediate risk zone, and the statin conversation could go either way. A coronary artery calcium test is the tiebreaker that turns "maybe" into a clear decision you and the patient can both stand behind.

What is a CAC test?

It's a noninvasive, low-dose, non-contrast CT that measures calcified plaque in the coronary arteries and reports a calcium score.

• Higher scores mean higher future risk of MI and stroke.
• It doesn't see soft (non-calcified) plaque, so a low score doesn't fully exclude CAD. Even so, CAC is a strong predictor of events.

Why consider it?

• It helps with ASCVD prevention decisions, like starting a statin or, selectively, low-dose aspirin.
• It improves risk communication and adherence by showing patients their arterial calcium number.

Who should get a CAC test?

Usually appropriate (a shared decision):

• Age 40 to 75 with a borderline to intermediate 10-year ASCVD risk by PREVENT (roughly 3% to under 10%) when the statin decision is uncertain. (This used to be framed as "5 to 20% by the Pooled Cohort Equations." PREVENT runs lower, so don't apply the old percentage range to a PREVENT score.)
• Patients with multiple risk enhancers (HTN, smoking, low HDL, CKD, strong family history of premature ASCVD) when a result would change management.

Generally not appropriate:

• Known CAD (prior MI, stent, CABG) or active chest pain. Use diagnostic pathways, not CAC.
• Very low risk adults.
• Under 40 years unless there's a compelling history or risk.
• Situations where the result won't change therapy: LDL 160 mg/dL or higher, LDL 190 mg/dL or higher, or diabetes, CKD 3 to 4, or HIV in the 40 to 75 age range, where a statin is indicated regardless of the scan.

Cost and radiation: typically $100 to $500 (often around $150). Radiation is roughly 1 mSv, which is low.

How to read the score

A flag on that bottom row: a CAC of 1000 or higher clearly qualifies for the <55 mg/dL ASCVD-equivalent target under the current guideline. Where exactly that target starts below 1000 is less settled in what I could verify, some secondary sources put the cutoff as low as CAC 300, which would move part of the 400 to 999 range into the <55 goal too. I couldn't confirm the exact number against the primary guideline text, so until you've checked it yourself, treat CAC 1000+ as the clear case and CAC 400 to 999 as at least a <70 target with a conversation about going lower.

For aspirin in primary prevention, consider it only case-by-case in age 40 to 59 with a 10% or higher 10-year risk and low bleeding risk. Generally avoid starting aspirin at age 60 or older for primary prevention.

How often to repeat?

Only if the result would change management. Intervals sometimes used:

• Low risk (under 5%): 5 to 7 years
• Borderline or intermediate (5 to 10%): 3 to 5 years
• Diabetes: around 3 years

If therapy is already clearly indicated and the patient has accepted it, there's no need to repeat.

What to do with the result

All scores:

• Lifestyle: heart-healthy diet, exercise, smoking cessation, healthy BMI.
• BP optimization and sleep. Consider lipoprotein(a) or other risk enhancers if decisions are still uncertain.

Medication decisions:

• Statin: base it on the score plus overall risk, and treat to the LDL-C target in the table above.
• Aspirin: selective primary prevention only (see the note above).
• Consider cardiology referral for CAC 400 or higher, atypical symptoms, or complex risk.

Patient counseling script you can paste

"A CAC scan is a quick, non-contrast CT that shows calcium in the heart arteries. A score of 0 means very low risk over the next 5 to 10 years, and higher scores mean higher risk. We'll use your number to decide whether a statin, and rarely aspirin, will help you avoid a heart attack or stroke. No matter the number, lifestyle (food, movement, sleep, and not smoking) still matters most."

Frequently asked questions

If the CAC score is 0, does that rule out heart disease?
No. CAC doesn't see soft, non-calcified plaque, so a 0 doesn't fully exclude CAD. It does mean very low short-term event risk, which is why it can support deferring a statin in the right patient.

Should I order a CAC test if a statin is already clearly indicated?
No. If the patient has LDL 160 or higher, LDL 190 or higher, diabetes/CKD 3-4/HIV in the 40 to 75 range, or known CAD, a statin is indicated regardless, so the scan won't change the plan.

When is the score high enough to involve cardiology?
A CAC of 400 or higher, atypical symptoms, or complex risk are reasonable reasons to refer, along with high-intensity statin and aggressive risk-factor control. A CAC of 1000 or higher, treated as an ASCVD-risk-equivalent, is a strong reason to refer.

What LDL-C target do I use for a CAC of 1000?
Under <55 mg/dL, the same target used for established ASCVD. That's clearly established for CAC 1000 and up. For scores in the 300 to 999 range, sources aren't fully consistent on whether the same <55 target applies, so treat <70 mg/dL as the safe floor in that band and confirm anything more aggressive against the full guideline.

A CAC test earns its place when it actually changes what you do next, mostly the statin decision in a borderline patient. Source: 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia, Circulation, March 2026. For a one-page version of the score thresholds, the Clinical Desk Reference keeps it handy, and the Primary Care Clinical Mastery Program covers ASCVD prevention end to end. For the basics that lead up to this, see the hyperlipidemia overview and statin intolerance.

Education only. Use clinical judgment and your local guidelines.

Written by Allison Sowders, MSN, APRN, FNP-BC, a practicing primary care nurse practitioner and founder of Nurse Practitioner Mentor. Reviewed September 2026.