A coronary calcium score is a measurement of the amount of calcium present in a person’s arteries. The presence of calcium in arteries is a sign of coronary artery disease, which is a strong risk factor for heart attack. The coronary calcium score is assessed through the use of a computer tomography (CT) scan, which evaluates the location and extent of artery calcification.
During a CT scan, a patient lies on his or her back. Electrodes are attached to the chest so that an electrocardiograph machine can record the heart’s electrical activity. Next, the scan is performed, during which the table on which the patient is lying moves through the CT scanning machine. This procedure uses multiple X-ray beams and sophisticated computer imaging equipment to generate images of the heart. The setup and CT procedure takes approximately 10 minutes.
Although the scan used to evaluate a coronary calcium score involves exposure to more radiation than with a conventional X-ray, the procedure is no more dangerous. During the scan, sensors detect the amount of radiation the person is exposed to, to ensure that exposure is minimal. As with conventional X-rays, however, pregnant women and women who suspect they are pregnant should avoid undergoing this scan.
The results of a CT scan for artery calcification are interpreted by a radiologist. He or she examines the scan images and assigns a coronary calcium score based on how extensive artery calcification is. When the test is negative, it means that there is very little or no calcification, and the individual being evaluated has a very low chance of having a heart attack in the next two to five years.
If the results of the test are positive, the person who has undergone testing has some coronary artery calcification. He or she is assigned a score based on the extent of calcification, and this score is one indicator that can be used to assess heart attack risk. The higher the score, the greater the chances that the individual might have a heart attack. This is only an approximate indicator, however, and it is not the only factor that a physician will consider when evaluating an individual’s risk of having a heart attack.
The coronary calcium score has some limitations that mean it is not suitable for every individual. Younger people, particularly those less than 50 years old, can have coronary artery disease even when calcification is not present. This means that someone might have the disease but show a negative result after a coronary CT scan. Another limitation is that someone with a rapid heartbeat might be unable to undergo the test. This is because a heart rate of 90 beats per minute or more can reduce the image quality of a coronary artery CT scan.