If you are looking into heart scans, two options come up often: a calcium score (also called CAC score) and a coronary CT angiogram (sometimes called CCTA). Both use a CT scanner and both look at your coronary arteries, but they show very different things. Choosing the right one can mean the difference between seeing part of the problem and seeing the whole picture.
What is a calcium score?
A calcium score is a quick, no-contrast coronary CT scan. You lie on a table, hold your breath for a few seconds, and the scanner takes images of your heart. The whole thing takes about ten minutes.
The scan looks for calcified (hard) plaque in your coronary arteries. A computer adds up the calcium and gives you your calcium score. Zero means no hard plaque was found. Above 100 means moderate buildup. Above 300 means significant buildup.
Think of it as a yes-or-no test for hard plaque. It is fast, affordable, and widely available. It can help you classify your risk. You can use the tool below to get your calcium score risk percentile.
Calcium score test one important blind spot: it cannot see soft plaque. And soft plaque is often the more dangerous kind. It can rupture and block the arteries, causing a heart attack.
What is a CT angiogram?
A heart CT angiogram is a more advanced CT scan. It captures exactly what a calcium score leaves out: the soft plaque and extent of blockages (narrowing) in your heart arteries. Your doctor can see the location, size, and composition of each plaque deposit. The scan itself is quick, but the full visit usually takes about 30 minutes with preparation.
Before the scan, a nurse injects contrast dye through an IV. The dye improves the visibility of your arteries so the CT machine can produce high-resolution images of the artery walls and any plaque buildup inside them.
Accuracy
CT angiogram has about 94 to 99 percent sensitivity for detecting blockages
Multiple studies confirm that coronary CT angiography is one of the most accurate non-invasive tests for finding coronary artery disease.
Head-to-head comparison
Here is how the two tests differ on the things that matter most.
| Category | Calcium score (CAC score) | CT angiogram |
|---|---|---|
| What it sees | Hard (calcified) plaque only | Hard plaque, soft plaque, and narrowing |
| Contrast dye | Not needed | Yes, through an IV |
| Radiation | Low | Slightly higher |
| Scan time | About 10 minutes | About 30 minutes including prep |
| Soft plaque | Cannot see it | Can detect and measure it |
| Blockages | Does not measure narrowing | Can measure narrowing |
| Cost | About $200 to $400 | About $2,000 to $3,000 |
Why the difference matters
Most heart attacks are caused by soft plaque that ruptures, not by hard plaque. That means a calcium score can miss the very thing that causes many heart attacks.
A calcium score of zero feels reassuring, and for many people it is. But it does not rule out soft plaque. A research study found that some people with a calcium score of zero still had non-calcified plaque on CT angiogram. The calcium score missed it entirely.
A calcium score above zero confirms plaque is present and is a clear signal to take action. But a score of zero does not guarantee clean arteries, especially if you have risk factors like elevated Lp(a) or a family history of heart disease.
What the clinical trials show
Two large trials changed how doctors think about CT angiogram.
SCOT-HEART trial
41 percent fewer heart attacks when CT angiogram guided treatment
The SCOT-HEART trial enrolled over 4,100 patients with stable chest pain. Those who received a CT angiogram in addition to standard care had 41 percent fewer heart attacks over five years compared to the standard-care-only group. A 10-year follow-up confirmed the benefit held long-term.
The PROMISE trial compared CT angiogram with stress testing in over 10,000 patients. CT angiogram found more coronary artery disease and led to more targeted treatments. When doctors can see the plaque directly, they make better decisions — and patients do better.
What the guidelines say
The American Heart Association supports calcium scoring for people at intermediate risk who want more information. It is a reasonable starting point given its low cost.
The 2021 American Heart Association chest pain guideline gives CT angiogram strong support as a first-line test for chest pain and suspected coronary artery disease, noting that it provides anatomical detail that stress tests cannot match.
Choose the right test for you
The right test depends on your situation. Here is a simple way to think about it:
- A calcium score makes sense if you have no symptoms, want a quick and affordable baseline, and are mainly looking for a yes-or-no answer about whether calcified plaque is present.
- A CT angiogram makes sense if you have symptoms like chest pain or shortness of breath, if you have risk factors like elevated Lp(a) or a strong family history, if you had a calcium score of zero but still want to rule out soft plaque, or if you want the most complete picture of your coronary arteries available without a catheter.
- Both tests together can be useful. A calcium score gives a quick, low-cost snapshot. If it shows plaque or if your risk profile warrants it, a CT angiogram can fill in the details your doctor needs to make the best plan.
- Talk to your doctor. Your medical history, risk factors, and symptoms all matter. A doctor who understands both tests can help you decide which one fits your situation.
The bottom line
A calcium score is a good starting point. It is quick, affordable, and confirms whether hard plaque is present. But it cannot see soft plaque or measure narrowing. Put simply: a calcium score gives you a partial picture. A coronary CT angiogram gives you the full picture.
A CT angiogram fills in those gaps by showing both types of plaque, measuring narrowing, and giving your doctor a detailed map of your arteries. Knowing what each test can and cannot do puts you in a stronger position to choose the right one.
At Veevo Health, we believe that clear, detailed heart imaging is the foundation of smarter prevention. Understanding your options is the first step.
Confidence in your heart health
Our advanced CT angiogram scan shows you the full picture of your heart arteries, giving you confidence in your heart health and the power to act early.