The Coronary Artery Calcium (CAC) score measures the amount of calcified plaque buildup within the walls of the heart’s arteries. This non-invasive test uses a specialized computed tomography (CT) scan to calculate the Agatston score, which quantifies established atherosclerosis. The primary purpose of the CAC score is to help physicians assess an individual’s risk of experiencing a future heart attack or stroke. This objective measure of underlying disease complements traditional risk factors like cholesterol and blood pressure.
Understanding the Coronary Artery Calcium Score
The CAC score is determined from a quick, non-contrast CT scan of the chest that images the coronary arteries. Calcium deposits appear bright white on the scan, allowing a computer program to measure their area and density. The resulting Agatston score is a numerical value reflecting the total burden of calcified plaque across all four major coronary arteries.
The presence of calcium in the arteries is a definitive sign of atherosclerosis, the hardening and narrowing of the arteries over time. Its accumulation in the coronary artery walls signals years of plaque development. The score measures the total amount of plaque, not the severity of any single blockage, distinguishing it from an angiogram. A higher score indicates a greater extent of coronary artery disease and a higher long-term risk of a major cardiac event.
Interpreting the Score Ranges
The CAC score classifications provide a framework for estimating cardiovascular risk. A score of zero indicates no identifiable calcified plaque, suggesting a very low risk of a heart attack over the next decade. This finding is associated with favorable long-term cardiovascular health.
Scores between 1 and 100 represent a low to intermediate risk, indicating mild calcified plaque. This range suggests the earliest stages of atherosclerosis and signals the need for increased attention to risk-modifying strategies. A score between 101 and 400 signifies a moderate amount of plaque, placing the individual in an intermediate to high-risk category.
A score above 400 is considered a high-risk finding, suggesting an extensive burden of calcified plaque. This level indicates a significantly elevated likelihood of a future cardiovascular event. The amount of plaque is often comparable to that found in patients who have already experienced a heart attack.
Benchmarking the Score for a 65-Year-Old
Age and Accumulation
The significance of a specific CAC score is heavily influenced by age, requiring the score to be benchmarked against others in the same demographic. A score alarming for a 45-year-old is often considered average for a 65-year-old, as plaque naturally accumulates over time. While zero remains the best score, it is found in only a minority of individuals in this age group.
Using Percentiles for Risk Assessment
To determine a favorable score for this age, physicians compare the patient’s result to percentiles derived from large population studies, such as MESA. A score that places a 65-year-old below the 75th percentile for their age and sex is considered favorable. This indicates the individual has less plaque than 75% of their peers, which is associated with a lower relative risk.
The median CAC score (the 50th percentile) for a 65-year-old man is typically higher than for a woman of the same age. For instance, a score of 150 might be near the 50th percentile for a man, but place a woman in a higher percentile. This difference highlights the need for sex-specific benchmarking to accurately gauge relative risk.
Physicians use this percentile information to refine the patient’s estimated 10-year risk of atherosclerotic cardiovascular disease (ASCVD). This personalized risk assessment helps guide treatment decisions beyond what traditional risk factors alone suggest. A score low for one’s age group indicates lower risk, while a score in the higher percentiles may prompt a more aggressive approach to prevention.
Actionable Steps After Receiving the Score
Score of Zero
Next steps following a CAC scan relate directly to the determined risk level. For a 65-year-old with a score of zero, the focus is on maintaining a heart-healthy lifestyle, including diet and physical activity. This low-risk result often allows for the withholding of preventive medications like statins or aspirin, provided no other high-risk factors are present.
Scores 1 to 100
If the score is in the mild range of 1 to 100, the primary recommendation involves aggressive risk factor modification through lifestyle changes. If the score is also above the 75th percentile for their age, a physician may suggest initiating moderate-intensity statin therapy. This aims to slow the progression of atherosclerosis and stabilize existing plaque.
Scores 101 to 400
A score between 101 and 400 necessitates a more intensive medical management strategy. Patients are encouraged to begin moderate to high-intensity statin therapy to achieve significant low-density lipoprotein (LDL) cholesterol reduction. Controlling blood pressure and blood sugar, along with daily low-dose aspirin, may also be considered based on the individual’s overall health profile.
Scores Above 400
For an extensive score above 400, management shifts to a highly aggressive, secondary prevention-like approach. This typically involves high-intensity statins. A physician may also recommend further testing, such as a stress test or a CT angiography, to check for significant blockages. Consulting a cardiologist or primary care physician is necessary to tailor these medical recommendations to the individual’s specific health needs.