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October 29, 2010

A “Calcium Score” may change your life

From NIH: http://www.nhlbi.nih.gov/health/dci/Diseases/cscan/cscan_all.html

What Is a Coronary Calcium Score?

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.

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
  • Calcium Score
  • 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 ofatherosclerosis 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