What Is a Coronary Calcium Scan?
A coronary calcium scan is a test that can help show
whether you have
coronary
heart disease (CHD), also called coronary artery disease. CHD is the most
common type of heart disease in both men and women.
In CHD, a substance called plaque (plak) builds up
inside your coronary arteries. These arteries supply your heart muscle with
oxygen-rich blood. Plaque is made up of fat, cholesterol, calcium, and other
substances found in the blood.
Plaque narrows your coronary arteries and reduces
blood flow to your heart muscle. It also makes it more likely that blood clots
will form in your coronary arteries. Blood clots can partly or completely block
blood flow to part of your heart muscle. This can cause chest pain or
discomfort called
angina
(an-JI-nuh or AN-juh-nuh) or a
heart
attack.
CHD also can lead to
heart
failure or
arrhythmias
(ah-RITH-me-ahs). Heart failure is a condition in which your heart can't pump
enough blood to meet your body's needs. Arrhythmias are problems with the rate
or rhythm of your heartbeat.
Overview
A coronary calcium scan looks for specks of calcium
(called calcifications) in the walls of the coronary arteries. Calcifications
are an early sign of CHD. The test can show whether you're at increased risk
for a heart attack or other heart problems before other signs and symptoms
occur.
Two machines can show calcium in the coronary
arteries—electron beam computed tomography (EBCT) and multidetector
computed tomography (MDCT). Both use an x-ray machine to make detailed pictures
of your heart. Doctors study the pictures to see whether you're at risk for
heart problems in the next 2 to 10 years.
A coronary calcium scan is simple and easy for the
patient, who lies quietly in the scanner machine for about 10 minutes. The
scanner takes pictures of the heart that show whether the coronary arteries
have calcifications.
Coronary Calcium Scan
Figure A shows the position of the
heart in the body and the location and angle of the coronary calcium scan
image. Figure B is the coronary calcium scan image, which shows calcification
in a coronary artery.
Outlook
A coronary calcium scan is most useful for people
who are at moderate risk for a heart attack. You or your doctor can calculate
your 10-year risk using the
Risk
Assessment Tool from the National Cholesterol Education Program.
People who are at moderate risk have a 10–20
percent chance of having a heart attack within the next 10 years. The coronary
calcium scan may help doctors decide who within this group needs treatment.
Other Names for a Coronary Calcium Scan
- Calcium scan test
- Cardiac CT for calcium scoring
Some people refer to a coronary calcium scan by the
name of the machine used to take pictures of the heart:
- Electron beam computed tomography (EBCT) or
electron beam tomography (EBT)
- Multidetector computed tomography (MDCT)
What To Expect Before a Coronary Calcium Scan
No special preparation is needed for a coronary
calcium scan. Your doctor may ask you to avoid caffeine and smoking for 4 hours
before the test.
For the scan, you'll remove your clothes above the
waist and wear a hospital gown. You also will remove any jewelry from around
your neck or chest.
What To Expect During a Coronary Calcium Scan
Coronary calcium scans are done in a hospital or
outpatient office. The x-ray machine that's used is called a computed
tomography (CT) scanner.
The technician who runs the scanner will clean areas
of your chest and apply sticky patches called electrodes. The patches are
attached to an
EKG
(electrocardiogram) machine to record your heart's electrical activity during
the scan. This makes it possible to take pictures of your heart when it's
relaxed, between beats.
The CT scanner is a large machine that has a hollow,
circular tube in the center. You'll lie on your back on a sliding table. The
table can move up and down, and it goes inside the tunnel-like machine.
The table will slowly slide into the opening in the
machine. Inside the scanner, an x-ray tube moves around your body to take
pictures of your heart. The technician controls the CT scanner from the next
room. He or she can see you through a glass window and talk to you through a
speaker.
You'll be asked to lie still and hold your breath
for short periods while each picture is taken. You may be given medicine to
slow down a fast heart rate. This helps the machine take better pictures of
your heart. The medicine will be given by mouth or injected into a vein.
A coronary calcium scan takes about 10 to 15
minutes, although the actual scanning takes only a few seconds. During the
test, the machine makes clicking and whirring sounds as it takes pictures. It
causes no discomfort, but the exam room may be chilly to keep the machine
working properly.
If you become nervous in enclosed spaces, you may
need to take medicine to stay calm. This isn't a problem for most people,
because the head will remain outside the opening in the machine.
What To Expect After a Coronary Calcium Scan
You'll be able to return to your normal activities
after the coronary calcium scan is done. Your doctor will discuss the results
of the calcium scan with you.
What Does a Coronary Calcium Scan Show?
After a coronary calcium scan, you'll get a calcium
score called an Agatston score. The score is based on the amount of calcium
found in your coronary (heart) arteries. You may get an Agatston score for each
major artery and a total score.
The test is negative if no calcium deposits
(calcifications) are found in your arteries. This means your chance of having a
heart
attack in the next 2 to 5 years is low.
The test is positive if calcifications are found in
your arteries. Calcifications are a sign of
atherosclerosis
(ATH-er-o-skler-O-sis) and
coronary
heart disease (CHD). (Atherosclerosis is a condition in which the arteries
harden and narrow due to plaque buildup.) The higher your Agatston score is,
the more severe the atherosclerosis.
You can use this
calculator from the National Heart, Lung, and Blood Institute
to see how your Agatston score compares with scores of people of your age and
ethnic background.
An Agatston score of 0 is normal. In general, the
higher your score, the more likely you are to have CHD. If your score is high,
your doctor may recommend more tests.
What Are the Risks of a Coronary Calcium Scan?
Coronary calcium scanning has very few risks. The
test isn't invasive, which means that no surgery is done and no instruments are
inserted into your body.
Coronary calcium scanning doesn't require an
injection of contrast dye to make your heart or arteries visible on x-ray
images.
Because an x-ray machine is used, you'll be exposed
to a small amount of radiation. Electron beam computed tomography (EBCT) uses
less radiation than multidetector computed tomography (MDCT). In either case,
the amount of radiation is less than or equal to the amount of radiation you're
naturally exposed to in a single year.
Key Points
- A coronary calcium scan is a test that can help
show whether you have
coronary
heart disease (CHD).
- A coronary calcium scan looks for specks of
calcium (called calcifications) in the walls of the coronary (heart) arteries.
Calcifications are an early sign of CHD.
- Two machines can show calcium in the coronary
arteries—electron beam computed tomography (EBCT) and multidetector
computed tomography (MDCT). Both use an x-ray machine to make detailed pictures
of your heart.
- A coronary calcium scan is most useful for
people who are at moderate risk for a
heart
attack. You or your doctor can calculate your 10-year risk using the
Risk
Assessment Tool from the National Cholesterol Education Program. People who
are at moderate risk have a 10–20 percent chance of having a heart attack
within the next 10 years.
- A coronary calcium scan may help doctors decide
who within the moderate risk group needs treatment.
- No special preparation is needed for a coronary
calcium scan. Your doctor may ask you to avoid caffeine and smoking for 4 hours
before the test.
- Coronary calcium scans are done in a hospital or
outpatient office. The x-ray machine that's used is called a computed
tomography (CT) scanner.
- A coronary calcium scan takes about 10 to 15
minutes. During the scan, you'll lie quietly on your back, while the CT scanner
takes pictures of your heart.
- You'll be able to return to your normal
activities after the calcium scan is done. Your doctor will discuss your
calcium scan results with you.
- The test is negative if your coronary arteries
have no calcifications. This means your chance of having a heart attack in the
next 2 to 5 years is low.
- The test is positive if calcifications are found
in your coronary arteries. Calcifications are a sign of
atherosclerosis
and CHD.
- After the scan, you'll receive a calcium score
called an Agatston score. The higher your Agatston score is, the more severe
the atherosclerosis.
- You can use this
calculator from the National Heart, Lung, and Blood Institute
to see how your Agatston score compares with scores of people of your age and
ethnic background.
- An Agatston score of 0 is normal. In general,
the higher your score, the more likely you are to have CHD. If your score is
high, your doctor may recommend more tests.
- Coronary calcium scanning has very few risks.
The test isn't invasive, which means that no surgery is done and no instruments
are inserted into your body. Coronary calcium scanning doesn't require an
injection of contrast dye to make your heart or arteries visible on x-ray
images.
- Because an x-ray machine is involved, you'll be
exposed to a small amount of radiation. The amount of radiation is less than or
equal to the amount of radiation you're naturally exposed to in a single year.
Links to Other Information About Coronary Calcium
Scans
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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DCI Home:
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