A calcium score test, also known as a coronary artery calcium (CAC) scan, is a non-invasive heart scan designed to assess an individual’s risk of developing coronary artery disease (CAD). This test helps determine the presence and extent of calcified plaque, which serves as an indicator of atherosclerosis, or hardening of the arteries. It provides insights into future cardiovascular events.
Understanding Calcium Score Tests
A calcium score test employs computed tomography (CT) technology to generate detailed images of the heart. It measures the amount of calcified plaque within the coronary arteries, the vessels supplying blood to the heart muscle. The CT scanner captures X-ray images, which are combined to create cross-sectional views of the arteries.
The presence and quantity of these calcium deposits indicate the extent of atherosclerosis, a condition where fatty substances, cholesterol, and other materials build up in the artery walls. Its accumulation in arteries signals past plaque formation, making the arteries stiffer and narrower. This test reveals calcified plaque that has been building up over time, rather than actively showing current blood flow blockages.
Interpreting Your Score
Calcium scores are quantified using the Agatston score, which considers both the area and density of calcified plaque. A score of zero signifies no detectable calcified plaque, indicating a very low risk of a heart attack in the subsequent two to five years. This outcome is favorable, even for individuals with other traditional risk factors.
Scores ranging from 1 to 99 suggest mild calcification, which is associated with a low to moderate risk of future cardiovascular events. A score between 100 and 399 indicates a moderate amount of plaque, signaling a relatively high risk of a heart attack within three to five years. Scores of 400 or higher represent extensive plaque buildup and are linked to a significantly elevated risk of heart attack. These scores serve as a predictor of risk, not a diagnosis of an immediate blockage, and are considered alongside other risk factors such as cholesterol levels, blood pressure, and family medical history for a comprehensive assessment.
Understanding Test Limitations
While valuable, the calcium score test has specific limitations in assessing heart risk. The scan primarily detects calcified plaque, meaning it does not identify soft, non-calcified plaque, which can also contribute to heart disease and pose a risk. Therefore, a low score does not guarantee a complete absence of all forms of coronary artery disease. Similarly, a high score indicates the presence of calcified plaque and increased risk, but it does not directly show active blockages or the degree of narrowing in the arteries.
The test is a snapshot of calcification and does not provide information on the stability of plaque or immediate blood flow issues. There is a potential for false negatives by missing soft plaque. Ultimately, the calcium score is one piece of the puzzle, not a standalone diagnostic tool for immediate cardiac events.
When a Calcium Score Test is Recommended
Calcium score tests are recommended for individuals who fall into an intermediate risk category for heart disease. This includes people aged 40 to 70 who have some risk factors but no clear high or low risk based on traditional assessments. For these individuals, the test provides a more precise risk assessment, which can guide decisions about preventive treatments like lifestyle modifications or medication.
The test is not recommended for individuals already diagnosed with heart disease, as the results would not significantly alter their management. It is also not advised for those at very low risk, where calcified plaque is unlikely to be present, or very high risk, where the findings would not change the aggressive treatment approach already indicated. A calcium score test is not considered a general screening tool for the entire population.