A coronary calcium score isn’t just another number on a lab report-it’s a direct look at the hidden buildup in your heart’s arteries. This simple, non-invasive CT scan detects calcium deposits that form as part of atherosclerotic plaque. And here’s the thing: you can have serious plaque buildup without feeling a single symptom. That’s why this test matters. It doesn’t wait for chest pain or a heart attack to sound the alarm. It tells you what’s happening inside your arteries right now.
What the Scan Actually Shows
The coronary calcium scan uses a specialized CT machine to take dozens of quick images of your heart. No needles. No contrast dye. Just you lying still for about 10 seconds while the machine captures cross-sections of your coronary arteries. The computer then calculates how much calcium is present-using something called the Agatston Score, named after the radiologist who created it in 1990.
This score doesn’t measure plaque directly. It measures the calcium that gets deposited inside plaque over time. Think of it like rust on a pipe. The rust isn’t the clog itself, but it tells you there’s been a slow buildup inside. In your arteries, calcium is a sign that plaque has been forming for years. And the more calcium, the more plaque you have.
Here’s what the numbers mean, based on guidelines from the American College of Cardiology and Cleveland Clinic:
- 0 = No detectable calcium. Low risk of heart disease.
- 1-10 = Minimal plaque. Still low risk, but not zero.
- 11-100 = Mild plaque. Early signs of artery disease.
- 101-400 = Moderate plaque. Your risk of a heart event is about 75% higher than someone with a score of zero.
- 401+ = Extensive plaque. High risk. This level often means significant narrowing of arteries.
These numbers aren’t just labels-they guide real medical decisions. A score above 100, especially if you’re in your 50s or 60s, often triggers doctors to recommend statins, even if your cholesterol looks fine. Why? Because calcium is a better predictor of heart attack risk than cholesterol alone.
Why It Beats Traditional Risk Calculators
Most doctors use tools like the Pooled Cohort Equations to estimate your heart disease risk. They look at age, blood pressure, cholesterol, smoking status, and diabetes. But here’s the problem: these tools get it wrong for up to 30% of people.
Studies in Circulation show that many people labeled as “low risk” by these calculators actually have high calcium scores. They’re walking around thinking they’re fine-until they’re not. Meanwhile, others with high cholesterol and normal scores may not need aggressive treatment.
The coronary calcium score cuts through the guesswork. It doesn’t estimate risk. It measures what’s actually in your arteries. A 2021 study in the Journal of the American College of Cardiology found that adding a calcium score to traditional risk factors improved accuracy by nearly 10%. That’s huge. It means more people get the right treatment-and fewer get unnecessary medications or procedures.
What It Can’t Do
But it’s not perfect. The scan only sees calcified plaque. About 20-30% of plaque is soft and doesn’t contain calcium yet. That means a score of zero doesn’t guarantee you’re free of heart disease. It just means you don’t have hardened plaque.
That’s why a coronary calcium scan isn’t used the same way as a coronary CT angiogram (CCTA). CCTA shows both soft and hard plaque, but it requires contrast dye and delivers more radiation. It’s also more expensive. The calcium scan is the first step-cheap, fast, and low-radiation-for people who don’t have symptoms but have risk factors.
It also doesn’t work well for people with chronic kidney disease. Their arteries often calcify from mineral imbalances, not from atherosclerosis. So a high score in those patients doesn’t mean the same thing.
Who Should Get One?
The guidelines are clear: this test is for asymptomatic adults with intermediate risk-that’s a 7.5% to 20% chance of a heart event in the next 10 years. That usually means:
- Men aged 45-75
- Women aged 55-75
- With one or more risk factors: high LDL, low HDL, high blood pressure, smoking, diabetes, or family history
It’s not for people with obvious heart disease, like chest pain or a previous heart attack. It’s also not for low-risk people under 40. But if you’re in that middle zone-where your doctor says, “You’re not high risk, but you’re not low risk either”-this test can be a game-changer.
In 2023, the Society of Cardiovascular Computed Tomography updated its guidelines to include people with LDL cholesterol over 160 mg/dL-even if they have no other risk factors. That’s a big shift. It means more people are being screened based on one strong marker.
What Happens After the Scan?
Getting the score is just the start. What matters is what you do next.
If your score is zero, keep doing what you’re doing. Focus on staying active, eating well, and avoiding smoking. You’re in the best possible group.
If your score is 1-100, your doctor may suggest lifestyle changes: more exercise, less sugar, better sleep. Sometimes they’ll start you on a low-dose statin, especially if you have other risk factors.
If your score is above 100, most cardiologists will recommend a statin-usually high-intensity if it’s over 300. That’s true even if your cholesterol is normal. Why? Because the plaque is already there. The statin isn’t just lowering cholesterol-it’s stabilizing the plaque so it doesn’t rupture and cause a clot.
And here’s something surprising: many people say their score was the wake-up call they needed. One Reddit user, age 52, had a score of 142. He’d ignored his doctor’s advice to quit smoking and take statins for years. After seeing his score, he quit smoking within a week and started medication. He said, “It wasn’t the cholesterol that scared me. It was the number.”
Cost, Coverage, and Accessibility
The scan usually costs between $100 and $300 out of pocket. Many private insurers cover it if your doctor recommends it, especially if you’re in the intermediate-risk group. But Medicare doesn’t cover it yet. That’s a big barrier.
Only about 15% of eligible patients actually get tested, according to the American Heart Association. Why? Lack of awareness, insurance confusion, and some doctors still thinking it’s “experimental.” But the data is solid. The MESA study showed that adding calcium scoring to risk assessment improved prediction accuracy enough to change treatment for nearly half of intermediate-risk patients.
Some imaging centers now use AI to reduce radiation by 40% without losing image quality. That’s a recent breakthrough. The technology is getting better, faster, and safer.
What’s Next?
The National Institutes of Health is running a 10,000-patient study called the CAC Consortium Study, tracking outcomes over five years. The goal? To set exact thresholds for when to start statins based on calcium score alone.
Right now, guidelines say: if your score is over 100 and you’re 40-75, talk to your doctor about statins. If it’s over 400, you’re in high-risk territory. But soon, we may have even clearer rules.
For now, the message is simple: if you’re in that middle zone, don’t wait for symptoms. Ask your doctor about a coronary calcium score. It’s the most direct way to know if your arteries are quietly filling with plaque-and whether you need to act now to stop it.
Is a coronary calcium scan the same as a stress test?
No. A stress test checks how your heart performs under physical strain, often by monitoring your EKG while you walk on a treadmill. It can show signs of reduced blood flow, but it doesn’t show plaque buildup directly. A coronary calcium scan shows actual calcium deposits in your arteries. Stress tests have a 15-20% false positive rate. Calcium scoring gives you direct anatomical evidence, with 95% sensitivity for detecting atherosclerosis.
Can a calcium score be too high?
There’s no upper limit that’s considered “too high.” A score over 1,000 means extensive plaque and a very high risk of heart attack. But even at that level, treatment can still reduce your risk significantly. Statins, blood pressure control, and lifestyle changes can stabilize plaque and prevent rupture. The goal isn’t to lower the score-it’s to prevent complications.
Does a zero calcium score mean I’m completely safe from heart disease?
Not entirely. A zero score means no calcified plaque, which is excellent. But about 20-30% of plaque is soft and doesn’t contain calcium yet. So you could still have early, non-calcified plaque. That’s why maintaining healthy habits matters-even with a zero score. It’s the best possible outcome, but not a guarantee.
How often should I get a coronary calcium scan?
If your score is zero and you’re healthy, you might wait 5-10 years before repeating it. If your score is moderate or high, your doctor may repeat it in 2-5 years to track progression. But frequent repeat scans aren’t usually needed unless your risk factors change dramatically-like gaining a lot of weight, starting smoking, or developing diabetes.
Do I need to prepare for the scan?
Yes, but minimally. Avoid caffeine and smoking for 4 hours before the test, since they can raise your heart rate and blur the images. You don’t need to fast. Wear comfortable clothing without metal zippers or buttons near your chest. The test itself takes less than 5 minutes, and you won’t feel anything during it.
Is the radiation from the scan dangerous?
The radiation dose is low-about 1-3 mSv, similar to a mammogram or a round-trip flight from New York to Los Angeles. That’s far less than a CT scan with contrast. The benefit of detecting early heart disease far outweighs the minimal radiation risk. Newer AI-enhanced scanners can reduce this even further by 40%.