The Problem With Cholesterol as a Risk Proxy
For decades, LDL cholesterol has been the primary metric used to assess cardiovascular risk. It's easy to measure, easy to understand, and responds to medication — which has made it a convenient clinical target.
But LDL alone is a crude predictor of who will actually have a heart attack.
Approximately 50% of people who have a first heart attack have LDL levels that were considered normal or low. Conversely, many people with elevated LDL never experience a cardiovascular event.
The reason is simple: LDL measures what's circulating in the blood. It doesn't measure what's actually in the arterial wall — the plaque that builds up over decades and eventually ruptures, causing a heart attack or stroke.
Cardiac calcium scoring measures the wall.
What a Coronary Artery Calcium (CAC) Scan Is
A CAC scan is a low-radiation CT scan (approximately 1 millisievert — less than a mammogram) that quantifies calcified plaque in the coronary arteries.
Calcified plaque is a marker of atherosclerotic burden — the actual structural disease in the arterial wall. It correlates directly with cardiovascular event risk in a way that cholesterol numbers alone do not.
The result is expressed as a calcium score:
- Score of 0: No detectable calcified plaque. Very low near-term cardiovascular risk. Studies show 10-year MACE (major adverse cardiovascular event) rates of approximately 1% in this group.
- Score 1–99: Mild plaque burden. Moderate risk requiring lifestyle and potentially medication intervention.
- Score 100–399: Moderate plaque burden. Significant cardiovascular risk; more aggressive risk factor management warranted.
- Score 400+: Extensive plaque burden. High risk; specialist evaluation often appropriate.
Why It Changes Clinical Decision-Making
A CAC score of 0 in a patient with elevated LDL may appropriately lead to a decision to defer statin therapy and focus on lifestyle modification.
A CAC score of 250 in a patient with 'borderline' LDL may appropriately accelerate medication initiation and more aggressive lifestyle intervention.
Without the CAC score, these decisions are made with less precision — often defaulting to treating the number (LDL) rather than the disease (atherosclerosis).
Who Should Get a CAC Scan
Current ACC/AHA guidelines recommend CAC scoring for adults ages 40–75 who are in an intermediate cardiovascular risk category and for whom the treatment decision (initiate statin vs. lifestyle only) is uncertain.
At PracticeRx, we recommend CAC scoring for a broader population:
- Adults over 35 with any family history of coronary artery disease or premature heart disease
- Anyone with two or more cardiovascular risk factors (hypertension, smoking, diabetes, obesity, dyslipidemia)
- Adults who want a definitive baseline cardiovascular risk assessment
- Anyone considering long-term statin therapy who wants data to inform the decision
The Broader Context
A CAC scan is one layer of cardiovascular assessment. A complete cardiovascular risk picture also includes:
- Advanced lipid panel (particle size and number, Lp(a), ApoB)
- Inflammatory markers (hsCRP, homocysteine)
- Blood pressure trend data
- Blood glucose and insulin resistance markers
- Cardiac imaging (echocardiogram for structural evaluation)
At PracticeRx, we don't run a CAC score in isolation. We interpret it in the context of your full metabolic and cardiovascular picture.
The Bottom Line
A cardiac calcium score is a 10-minute scan that tells you whether you have atherosclerosis — the actual disease that causes heart attacks — not just risk factors for it.
For most adults over 40, it is the single most valuable cardiovascular screening test available. And most people have never had one.
PracticeRx coordinates cardiac calcium scoring and comprehensive cardiovascular risk assessment as part of our preventative medicine protocol.