The Coronary Artery Calcium (CAC) scan is a non-invasive computed tomography (CT) tool that directly measures subclinical atherosclerosis, the buildup of calcified plaque in the arteries. The result, known as the Agatston score, quantifies the amount of calcified plaque present in the coronary arteries to assess an individual’s cardiovascular risk. This score is a powerful independent predictor of future heart events, offering insight beyond traditional risk factors like cholesterol and blood pressure. The scan helps reclassify risk, particularly for asymptomatic individuals in an intermediate-risk category.
What the Coronary Artery Calcium Scan Measures
The scan directly measures the presence and density of calcified atherosclerotic plaque within the walls of the heart’s arteries. Atherosclerosis is a disease process where fatty deposits accumulate and harden, narrowing the blood vessels. Although the scan does not detect soft, non-calcified plaque, the presence of calcium confirms that the disease process is underway.
The measurement is quantified using the Agatston score, which is derived from the area and density of the identified calcium deposits. The CT scanner identifies high-density areas and calculates a weighted score for each lesion. The total Agatston score is the sum of these individual scores from all four major coronary arteries. A higher score indicates a greater burden of calcified plaque and a more advanced stage of coronary artery disease (CAD).
Interpreting Calcium Score Ranges
The Agatston score is grouped into categories that correlate with increasing levels of cardiovascular risk. A score of zero is the most favorable result, indicating no identifiable calcified plaque and correlating with a very low risk of a heart event. This result often supports deferring statin therapy and focusing on continued lifestyle modifications.
A score ranging from 1 to 100 indicates a minimal to mild plaque burden and a mildly increased risk. This level prompts consideration of statin therapy and more aggressive modification of risk factors. Scores between 101 and 400 represent a moderate plaque burden, correlating with a moderate to high risk of a future event. This result typically leads to the initiation of moderate- to high-intensity statin therapy and further evaluation.
A score greater than 400 signifies an extensive plaque burden and a high risk of a heart attack or stroke. The risk in this category is comparable to that of a patient who has already experienced a cardiovascular event. These categories provide a standardized framework, but the significance of any specific score must be viewed through the lens of a patient’s age and sex.
Risk Context for a 60-Year-Old Male
For a 60-year-old man, a “normal” score is determined by a percentile rank, comparing his result to thousands of other men in the same age group. Plaque accumulation increases with age, so a score considered normal for a 60-year-old is higher than for a younger man. A favorable score falls below the 50th percentile for his age, sex, and race group, meaning he has less calcified plaque than half of his peers.
Data from large population studies, such as the Multi-Ethnic Study of Atherosclerosis (MESA), determine these age- and sex-specific percentile thresholds. For a white male aged 60 to 64, the median score (50th percentile) is often in the range of 50 to 100 Agatston units. A score near this median suggests an average amount of plaque for his demographic.
The threshold for clinical concern is often set at the 75th percentile, where the score is considered high relative to his peers. For a 60-year-old male, this 75th percentile often falls between 150 and 300 Agatston units, though this varies by race. A score at or above the 75th percentile, regardless of the absolute number, prompts more aggressive medical management.
Following Up After Your Scan Result
The CAC score is not a diagnosis but a powerful tool informing an individualized medical action plan. After receiving the result, the most important step is consulting a physician to integrate the score with all other traditional risk factors. This comprehensive review determines the intensity of the necessary follow-up, ranging from lifestyle modifications to pharmacotherapy.
For a 60-year-old man with a score of zero, the focus remains on continued primary prevention, including diet and physical activity. A zero score provides strong reassurance, though a repeat scan may be considered in five to seven years based on his overall risk profile.
If the score is 100 or higher, it typically triggers a discussion about intensive risk factor modification and medication use. A score above 100 often leads to the initiation or intensification of statin therapy to aggressively lower LDL-C levels. For scores of 300 or greater, a high-intensity statin regimen is often recommended. In cases of extensive calcification (above 400), a physician may also consider prescribing low-dose aspirin for primary prevention, provided the bleeding risk is low.