Coronary Artery Calcium Test (CAC)

What is CAC?

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

• Higher scores = higher future risk of MI and stroke.

• It doesn’t see soft (non-calcified) plaque, so a low score doesn’t fully exclude CAD—but CAC remains a strong predictor of events.

Why consider it?

• Helps with ASCVD prevention decisions (e.g., starting a statin or—selectively—low-dose aspirin).

• Improves risk communication and adherence by showing patients their arterial calcium “number.”

Who Should Get a CAC?

Usually appropriate (shared decision):

• Age 40–75 with 5–20% 10-year ASCVD risk (borderline to intermediate) when the statin decision is uncertain

• Patients with multiple risk enhancers (e.g., HTN, smoking, low HDL, CKD, strong FH 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

• <40 years unless compelling history/risk

• Situations where the result won’t change therapy (e.g., LDL ≥190 or diabetes age 40–75 where statins are indicated regardless)

Cost & radiation: typically $100–$500 (often ~$150); radiation roughly ~1 mSv (low).

How to Interpret the Score

Aspirin for primary prevention: consider only case-by-case in age 40–59 with ≥10% 10-yr risk and low bleeding risk; generally avoid starting aspirin ≥60 y for primary prevention.

How Often to Repeat?

Only if the result would change management. Typical intervals sometimes used:

• Low risk (<5%): 5–7 years

• Borderline/intermediate (5–10%): 3–5 years

• Diabetes: around 3 years
  (If therapy is already clearly indicated and accepted, no need to repeat.)

What To Do With the Result (Your Game Plan)

All scores:

• Lifestyle: heart-healthy diet, exercise, smoking cessation, healthy BMI

• BP optimization and sleep; consider lipoprotein(a) or other risk enhancers if decisions remain uncertain

Medication decisions:

• Statin: base on score + overall risk (see table).

• Aspirin: selective primary prevention only (see note above).

• Consider cardiology referral: CAC ≥400, atypical symptoms, or complex risk.

Patient Counseling Script (copy/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 in the next 5–10 years; higher scores mean higher risk. We’ll use your number to decide if a statin(and rarely aspirin) will help you avoid a heart attack or stroke. Regardless of the number, lifestyle—food, movement, sleep, and not smoking—remains critical.”

Education only; use clinical judgment and your local guidelines.

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