The Coronary Artery Calcium (CAC) scan is a non-invasive tool that uses computed tomography (CT) to assess an individual’s risk of experiencing a future heart attack or other coronary event. This quick procedure detects and measures the amount of calcified plaque present within the walls of the heart’s arteries. The presence of this calcium is a direct sign of atherosclerosis, commonly known as hardening of the arteries, which develops over time, often long before any symptoms appear. The resulting score from this scan provides a quantitative measure of the total burden of this plaque, allowing physicians to better tailor preventive treatment strategies.
The Agatston Score: What the Raw Number Indicates
The raw, absolute numerical result of a CAC scan is known as the Agatston score, named after the cardiologist who pioneered the method. This score is calculated by factoring in both the area of the calcified plaque lesions and the density of the calcium within those lesions. The Agatston score translates the visual evidence of plaque into a single number that reflects the total quantity of calcification in the coronary arteries.
A score of zero is the best possible result, indicating no detectable calcified plaque and suggesting a very low risk of a coronary event over the next several years. As the score increases, the risk of a heart attack or other adverse event rises proportionally. A score between 1 and 99 signifies mild plaque deposits, placing a person in a low-to-moderate risk category.
When the score falls into the 100 to 299 range, it suggests moderate plaque burden and is associated with a moderate risk of a heart event. Scores of 300 or higher represent extensive calcification and are considered a sign of high risk for coronary heart disease.
Interpreting the 90th Percentile Ranking
While the Agatston score provides the absolute quantity of plaque, the percentile ranking offers a relative assessment by comparing an individual’s score to others in their demographic. This comparison is made against reference data, considering people of the same age, sex, and ethnicity. The percentile places the patient’s calcium burden into the context of their peer group, which helps determine if the pace of plaque development is accelerated.
A result in the 90th percentile means that the individual has more coronary artery calcification than 90% of the people in their specific age, sex, and ethnic group. This finding signals accelerated atherosclerosis compared to their peers. For instance, a relatively low Agatston score considered mild in an older person might be highly significant if it places a younger person in the 90th percentile.
The clinical significance of a 90th percentile score is that it elevates the patient’s risk profile to a high-risk classification, regardless of the raw Agatston number. Even if the absolute score is below the traditional high-risk threshold of 300, a percentile this high indicates a need for aggressive preventive action. This suggests the underlying disease process is progressing much faster than expected for that demographic.
The percentile is particularly informative for younger individuals, such as those under 45, where even a non-zero Agatston score can place them in a high percentile. This comparative measure helps physicians identify patients who have an unexpectedly high burden of disease for their age, prompting earlier and more intensive intervention than the absolute score alone. Therefore, the 90th percentile serves as a clear warning sign of premature or excessive coronary artery disease.
Next Steps Following a High Calcium Score
A high calcium score, especially one landing in the 90th percentile, necessitates a comprehensive discussion with a cardiologist or primary care physician. The immediate next step involves a thorough review of all traditional cardiovascular risk factors, such as cholesterol levels, blood pressure, blood sugar, and family history. This consultation leads to the development of a personalized strategy to mitigate future risk.
Intervention typically includes aggressive lifestyle modifications centered on a heart-healthy diet and regular physical activity. Specific changes involve reducing saturated fats and sodium intake while increasing healthy fat sources like nuts and olive oil. Patients should aim for at least 150 minutes of moderate exercise weekly. Smoking cessation is also required for any individual with detectable coronary calcium.
Pharmacological management is often initiated or intensified following a high score to slow the progression of the disease. Moderate-to-high intensity statin therapy is routinely recommended to lower cholesterol, particularly low-density lipoprotein (LDL) cholesterol, even if pre-test cholesterol levels were only moderately elevated. For scores above 100, or those in a high percentile, the use of low-dose aspirin may also be considered, based on the individual’s overall bleeding risk.
For individuals with very high scores, such as those over 400, the physician may recommend further non-invasive testing, like a stress test, to check for significant blood flow blockages. The goal of these steps is not to reverse the calcification, which is generally permanent, but to stabilize the existing plaque and prevent the formation of new, potentially unstable, soft plaque that can lead to a heart attack. A high score provides the opportunity to prevent a future adverse event through decisive medical and behavioral changes.