The Coronary Artery Calcium (CAC) score is a non-invasive tool that assesses an individual’s risk for future heart problems. This test uses advanced imaging to look for early signs of atherosclerosis, a disease where plaque builds up in the arteries. Understanding the CAC score provides insight into cardiovascular health, particularly for those with an intermediate risk profile. Its interpretation changes when compared to the scores of others in the same age group.
Defining the Coronary Artery Calcium Score
The Coronary Artery Calcium test is a specialized, non-contrast computed tomography (CT) scan of the chest. This procedure measures the amount of calcified plaque within the coronary arteries, the vessels supplying blood to the heart muscle. The presence of calcium indicates that atherosclerotic plaque formation has begun. The scan focuses only on calcified plaque and cannot detect “soft,” non-calcified plaque.
The final result is reported as an Agatston score, the official metric quantifying the total burden of calcification. This score is calculated by factoring the area and density of the detected calcium deposits. This numerical value directly correlates with the cumulative amount of hardened plaque in the coronary arteries.
Interpreting the Calcium Score Ranges
The Agatston score offers a direct measure of the risk for a major cardiac event, independent of age or other factors. A score of zero is optimal and suggests a very low risk of a heart attack over the next decade, meaning the individual is free of detectable calcified plaque. This finding has a negative predictive value for a cardiac event exceeding 99%.
A score between 1 and 100 indicates a mild amount of calcified plaque and is associated with a low to moderate risk of coronary artery disease. This small burden often warrants intensified lifestyle changes. Scores from 101 to 400 represent a moderate plaque burden, placing the individual in a moderate to high-risk category for a future cardiac event and prompting consideration of aggressive preventive therapies.
A CAC score above 400 signifies an extensive plaque burden and is associated with a severe risk of a heart attack or other coronary event. Individuals with scores in this high range have event rates comparable to those already diagnosed with cardiovascular disease. Very high scores exceeding 1,000 are considered extremely high risk, often requiring the most aggressive medical management.
Understanding Expected Scores by Age and Percentile
Plaque accumulation naturally progresses over time; therefore, a score alarming for a young person might be expected for an older individual. The percentile ranking compares a person’s score to others of the same age, sex, and ethnicity. The percentile indicates the percentage of people in the reference group who have a lower CAC score.
For example, a man in his late 40s with a CAC score of 10 might be concerned, but the median score (50th percentile) for men aged 45–54 is often zero. Conversely, a man aged 55 to 59 with a score of 72 may only be at the 75th percentile. The median score for individuals aged 65 to 75 can reach 110 Agatston units, illustrating the impact of age on the expected plaque burden.
A non-zero score in a young patient is particularly significant because it suggests an accelerated process of atherosclerosis relative to their peers. For instance, any detectable calcification in a woman under 55 or a man under 45 often places them in a higher-risk percentile (75th or higher). This highlights that a high percentile score in a younger person is more concerning than a similarly high absolute score in an older person, as it indicates a more aggressive disease trajectory.
Follow-Up and Management Based on Score Results
The CAC test is used for asymptomatic individuals aged 40 to 75 who have an intermediate risk for atherosclerotic cardiovascular disease. The results refine the individual’s risk profile and guide preventive treatment decisions. For patients with a CAC score of zero, the risk is reclassified as very low, and doctors typically withhold cholesterol-lowering statin therapy.
For any score greater than zero, the presence of calcified plaque warrants aggressive modification of cardiovascular risk factors. Individuals with scores in the 1 to 99 range are encouraged to adopt intensified lifestyle changes, including diet and exercise improvements. Statin therapy is often favored for patients in this range, particularly if they are over 55 or their score is above the 75th percentile for their age and sex.
A CAC score of 100 or greater is a significant finding that typically triggers the initiation of statin therapy, often at a moderate or high intensity. For these high-risk scores, the goal for low-density lipoprotein cholesterol is usually set at an aggressive target, such as below 70 mg/dL. Low-dose aspirin therapy may also be considered for individuals with scores above 100, alongside optimizing blood pressure and blood sugar control.