When we talk about preventing heart disease, cholesterol numbers are only part of the story. Tests such as ApoB, LDL cholesterol, Lp(a), blood pressure, blood sugar, and inflammatory markers can tell us about cardiovascular risk—but sometimes we want to answer a more direct question: Is there actually plaque in the coronary arteries? Two tests you may hear about are a coronary artery calcium (CAC) score and Cleerly coronary plaque analysis. They both look for coronary artery disease, but they provide very different information.
First: Soft Plaque vs. Hard Plaque
Atherosclerosis develops when cholesterol-containing particles become trapped in the artery wall and plaque begins to form. Plaque isn’t all the same. Non-calcified or “soft” plaque generally represents an earlier stage of atherosclerosis and cannot be seen on a standard calcium score. Over time, some plaque becomes calcified or “hard.” Calcium is therefore an important marker that atherosclerosis is present—but it doesn’t represent the entirety of someone’s plaque burden.This distinction matters because a person can have a calcium score of zero and still have non-calcified coronary plaque.
Coronary Calcium Score: The Simple Screening Test
A coronary artery calcium score is a quick, non-contrast CT scan that measures calcified plaque in the coronary arteries. The result is reported as an Agatston score. In general, the higher the score, the greater the burden of calcified coronary atherosclerosis and the higher the cardiovascular risk. CAC scoring has extensive evidence behind it and is incorporated into cardiovascular prevention guidelines as a way to refine risk and help guide decisions about preventive treatment.
Pros of a Calcium Score
- Quick and widely available
- Relatively inexpensive
- No IV contrast
- Low radiation exposure
- Very well studied for predicting cardiovascular risk
- Particularly useful when we’re trying to decide how aggressively to treat cholesterol
Cons
The biggest limitation is simple: A calcium score only measures calcified plaque. It doesn’t directly show us non-calcified plaque, plaque composition, or whether plaque is narrowing a particular coronary artery. This becomes particularly important in younger people and others who may have developing atherosclerosis that has not yet accumulated much calcium.
What Is Cleerly?
Cleerly is different. Rather than performing a separate type of scan, Cleerly uses advanced software and AI to analyze images obtained from a coronary CT angiogram (CCTA). A CCTA requires IV contrast and provides detailed images of the coronary arteries. CCTA can identify both obstructive and non-obstructive coronary artery disease and characterize plaque composition, including non-calcified plaque and certain higher-risk plaque features. Cleerly takes this information further by quantifying and characterizing coronary plaque throughout the arteries. In other words, instead of simply asking: “How much calcium is there?” we can ask: “How much plaque is actually there—and what kind of plaque is it?”
Pros of Cleerly/CCTA
- Detects non-calcified (“soft”) plaque
- Detects calcified plaque
- Provides a more complete estimate of total plaque burden
- Shows where plaque is located
- Evaluates whether plaque is narrowing the coronary arteries
- Can provide information about plaque composition and potentially higher-risk plaque characteristics
Cons
There are trade-offs. CCTA requires IV iodinated contrast, making kidney function and contrast allergy relevant considerations. It is more expensive and involved than a calcium score, may not be covered in every situation, and generally involves more radiation than a simple CAC scan—although modern CCTA radiation doses have decreased considerably. And importantly, more information isn’t always better if it isn’t going to change what we do.
So Which One Do I Prefer?
It depends on the question we’re trying to answer. For many asymptomatic adults, a calcium score remains an excellent first-line tool. It’s inexpensive, quick, well validated, and can meaningfully change how we think about cardiovascular risk and cholesterol treatment. But there are situations where I want more information. For example, someone may have a strong family history of premature heart disease, markedly elevated ApoB or Lp(a), or other significant risk factors—and yet have a calcium score of zero. In that situation, the question of non-calcified plaque becomes particularly interesting. A CCTA with advanced plaque analysis such as Cleerly can potentially give us a much more detailed picture. One important point: a calcium score of zero is very reassuring, but it does not literally mean “zero plaque.” It means that no calcified coronary plaque was detected.
The Bottom Line
I think of these tests as answering two slightly different questions:
Calcium score:
“How much calcified coronary plaque do you have, and what does that tell us about your future cardiovascular risk?”
CCTA/Cleerly:
“What is actually happening inside your coronary arteries—including both calcified and non-calcified plaque?” For some patients, a calcium score provides exactly the information we need. For others—particularly when cardiovascular risk factors and the calcium score don’t seem to tell the same story—a deeper look at total plaque burden may be worth considering. The goal isn’t to order the fanciest test. It’s to choose the test that gives us information we can actually use to make better decisions about prevention.