Coronary Calcium Scan: The Test That Predicts Heart Attacks Before They Happen

Heart disease often develops quietly. You may feel healthy, but plaque could already be building inside your arteries. This hidden buildup can suddenly lead to a heart attack. That’s why doctors sometimes recommend a coronary calcium scan.

It is a special computerised tomography (CT) scan of your heart. A simple test which helps to see for calcium buildup in the heart arteries, which leads to narrowing of the arteries and reduced blood flow to the heart. A coronary calcium scan can spot the early warning signs before symptoms appear.

What is a coronary calcium scan, and how does it work?

A coronary calcium scan, also known as a coronary CT calcium scan or coronary artery calcium scan test, is a special type of CT scan that looks for calcium deposits in the arteries of your heart.

Here’s how it works:

• The scan uses X-ray technology to take detailed pictures of your heart.
• Calcium shows up clearly on these images.
• The test measures how much calcium is present and gives you a coronary calcium scan score (also called an Agatston score).

The scan is painless. You lie on a table that slides into a CT machine. Sticky patches with sensors are placed on your chest to monitor your heartbeat. The test usually takes about 10 to 15 minutes.

Some people wonder about radiation. So, how much radiation is in a coronary calcium scan? It’s a small amount, considered safe, and lower than what you’d get from many other medical imaging tests.

Why is calcium in the arteries a red flag for heart disease?

Your arteries are like highways that carry blood to your heart. Over time, fat, cholesterol, and calcium can build up inside them. This buildup is called plaque.

Plaque makes arteries stiff and narrow. When arteries narrow, less blood and oxygen reach your heart. This raises the risk of chest pain, heart attacks, and strokes.

Calcium is especially important because:

• Its presence signals long-term plaque buildup.
• Once calcium appears, it usually stays—showing a history of artery damage.
• More calcium generally means more plaque and higher risk.

That’s why spotting calcium early is such a strong warning sign of heart disease.

Who should consider getting a coronary calcium scan?

A coronary artery calcium scan isn’t for everyone. Doctors don’t recommend it as a routine test for all patients. Instead, it’s most helpful if your risk of heart disease is uncertain or moderate.

You may be a good candidate if:

• You have a strong family history of early heart disease.
• You have risk factors like high cholesterol, high blood pressure, diabetes, or smoking.
• You are between ages 40 and 70 and not clearly at low or high risk.
• You and your doctor want more information before starting or adjusting medications.

It may not be useful if you’ve already had a heart attack, stents, or bypass surgery, since those conditions already confirm artery disease.

If you’re wondering, “Where can I get a coronary calcium scan?”—the test is offered at many hospitals and imaging centres. In some cities, clinics advertise walk-in scans, often without a referral.

What does your calcium score mean?

The main result of the test is your coronary calcium scan score. This number reflects the total area and density of calcium in your heart arteries.

Here’s what the scores usually mean:

• 0: No calcium. Low risk of heart attack.
• 1 to 99: Small amount of plaque. Mild risk.
• 100 to 300: Moderate plaque. Higher risk of a heart attack in the next few years.
• Over 300: Extensive plaque. High risk of serious heart disease.

Sometimes, the score is also compared to others of the same age and sex. For example, a score in the 75th percentile means your arteries have more calcium than 75% of people like you.

How accurate is it in predicting future heart attacks?

The coronary artery calcium scan is one of the best tools available for spotting hidden risk. Research shows that calcium scores are strongly linked to future heart problems.

In fact:

• A score of zero often predicts a very low risk of heart attack in the next 5 to 10 years.
• Higher scores match up with higher rates of heart attacks and cardiac events.
• The scan provides information beyond traditional risk factors like cholesterol or blood pressure.

That said, it’s not perfect. It doesn’t show soft plaque that hasn’t hardened into calcium yet. And it doesn’t replace lifestyle changes or other heart tests your doctor may recommend.

What should you do if your calcium score is high?

Getting a high score can feel scary. But it’s also an opportunity—because now you know your risk, and you can take action.

If your coronary calcium scan score is elevated, your healthcare team may suggest:

• Medication changes: starting or adjusting cholesterol-lowering drugs like statins.
• Lifestyle changes: eating a heart-healthy diet, exercising regularly, quitting smoking, and managing stress.
• Weight management: setting new goals if needed.
• More testing: In some cases, stress tests or advanced imaging may be ordered.
• Closer follow-up: Regular appointments to track your progress.

The scan itself is usually not repeated once calcium is found. Instead, the focus is on slowing down or stopping the buildup of new plaque.

Final Thoughts

A coronary calcium scan is a quick, painless test that looks for calcium in your heart arteries. It can help predict your risk of a future heart attack, often before any symptoms appear.

The test isn’t for everyone, but if your risk is uncertain, it can provide valuable insight. A score of zero is reassuring. A higher score means it’s time to take action with your doctor’s guidance.

While the test itself doesn’t prevent heart disease, the knowledge it provides can help you and your healthcare team make smarter decisions about your treatment, lifestyle, and long-term health.

FAQs

Is a coronary calcium scan dangerous?

No, it’s a safe, non-invasive CT scan with very low radiation exposure.

Does a high calcium score always mean I will have a heart attack?

No, it indicates higher risk, but it doesn’t guarantee a heart attack.

Is this test useful if I have no symptoms of heart disease?

Yes, it helps identify hidden risk before symptoms appear.

How often should I repeat the coronary calcium scan?

Usually every 3–5 years, but your doctor may adjust based on risk.

Will this scan detect blocked arteries or soft plaque?

It only measures hard calcium deposits, not soft plaque or exact blockages.

Can lifestyle changes lower my calcium score over time?

No, the score usually doesn’t decrease, but healthy habits slow progression.