CT Calcium Score

CT Calcium Score Test Overview

A CT calcium score goes by various terms, the most popular being:

1. Coronary calcium score
2. Cardiac calcium score
3. Coronary artery calcium score (CAC score)
4. CT coronary calcium scan
5. Coronary artery calcium scan
6. Coronary artery calcium scoring

While this might seem intimidating, this type of cardiac CT scan is, in fact, a straightforward and non-invasive test. It can lead to the early detection of coronary artery disease and help in the prevention of heart attacks.

Get informed about your health. Learn more about CT cardiac calcium scoring in our resources below. 

How a Calcium CT Score Test is Done   

A calcium CT scan uses X-rays to create detailed images of your heart’s arteries. The scan is synchronised with your heartbeat using an electrocardiogram (ECG) to capture clear images of blood vessels between heartbeats, when your heart is at its most still.

The entire scan typically takes only 10-15 minutes and requires no injections or special preparation.

The radiologist examines the multiple images and identifies any calcium deposits in your coronary arteries. Each deposit is measured based on its density and area. These measurements are combined to produce your total coronary artery calcium (CAC) score, expressed in Agatston units. 

What a CT Calcium Score Can Tell You

A CT calcium score measures the amount of calcified plaque in your coronary arteries.

• A low score suggests minimal plaque 
• A high score indicates more extensive plaque buildup over the years

This helps your doctor understand your future risk of a heart attack or stroke and plan for possible treatment decisions.

What a CT Calcium Score Cannot Show

A calcium score does not measure how narrow your arteries are. To see whether blood flow is restricted, you may need other tests, such as:

• CT coronary angiogram (a dye-enhanced CT scan)
• An invasive coronary angiogram, which looks directly inside the arteries.

When to Get a CT Calcium Scan 

The European Society of Cardiology (ESC) recommends using a cardiac CT calcium score for people at moderate risk of heart disease. This means having about a 1–5% chance of a fatal heart event, such as a heart attack or stroke, in the next 10 years. The estimate comes from the SCORE (Systematic COronary Risk Evaluation) calculator.

When a CAC Test Can Be Helpful

You may benefit from a CT coronary calcium score test if you:

• Have no chest pain or related symptoms, but want to know your long-term heart disease risk
• Are unsure about starting a statin based on your current risk factors, like a family history of coronary disease
• Score between 1–99 units, especially if you are under 45, which may suggest early plaque buildup
• Score 100 or higher, in which case statin therapy is usually recommended

Who Should Not Have a CAC Test

A CAC test is not recommended if:

• You are already taking a statin
• You have known heart or coronary artery disease 

You have medical conditions where a statin is recommended regardless of CAC score, including:

• Diabetes
• Current smoking
• Familial hypercholesterolaemia (very high inherited cholesterol)

In these cases, the test usually won’t change your treatment plan.

How Coronary Artery Build-Up Starts & Develops

To understand what a calcium score CT scan can and can’t tell you, it helps to know how atherosclerosis (the “furring up” of arteries) develops.

Your coronary arteries have 3 layers:

1. Outer layer
2. Middle smooth-muscle layer
3. Thin inner lining called the endothelium

The endothelium acts as a waterproof barrier and releases substances that help your artery function normally. Once the lining is damaged, cholesterol particles can stick to the area. They become oxidised, triggering white blood cells to move in and try to clear them.

What Damages the Artery Lining

Over time, several factors can injure the endothelium, including:

• Toxins from cigarette smoke
• Certain types of cholesterol, especially LDL cholesterol
• Long-term high blood pressure (hypertension).

How Plaque Forms

White blood cells take up the cholesterol, become overloaded, and eventually die. When they do, they release cytokines, which signal that repair is needed.

Your body responds by sending smooth muscle cells to form a fibrous cap over the area. This forms a plaque that acts as a protective barrier between the bloodstream and the inflamed tissue beneath.

As the plaque grows, the artery becomes narrower, and blood flow becomes more disturbed. If the fibrous cap becomes unstable and cracks, a blood clot can form.

• A partial clot may heal over and continue to narrow the coronary artery.
• A sudden full blockage can cause a heart attack. 

Why Calcium Deposits Build Up

As plaque matures, your body may lay down calcium deposits within it. This makes the coronary artery more rigid and less able to expand, which can worsen blood pressure over time.

After starting treatments like statins, plaque can become denser and more stable. Treatments may sometimes lead to a higher calcium score, even though your overall risk of heart attack or stroke is actually decreasing.

Save loved ones hours of explanation about tests like cardiac CT scans. Subscribe to our channel for regular heart health content from leading cardiologist, Mr Birdi.

Keyhole Heart Clinic: Experts in Early Heart Risk Detection 

Heart screening services feel fragmented, listing tests without focusing on the patient. What matters isn’t a one-off snapshot, but the trend over time. Your calcium score today helps, but what it looks like in 3–5 years matters more.

We often see patients who have had multiple tests, gone through the CT scanner, and even seen several clinicians, yet still leave without real reassurance.  That is why we take a different approach to heart screenings at The Keyhole Heart Clinic.

It starts with a consultant-led conversation, tailored testing, and a long-term plan that adapts as you do. As our clinic director and renowned surgeon, Inder Birdi says: