The Coronary Artery Calcium (CAC) test, commonly known as a cardiac calcium scan, is a non-invasive imaging procedure that provides a direct look inside the arteries supplying the heart. It is designed to detect and quantify calcified atherosclerotic plaque, which is the physical manifestation of coronary artery disease. By measuring the amount of this hardened material, the test helps clinicians determine an individual’s future risk of a heart attack or stroke.
What the Cardiac Calcium Test Measures
The test employs a specialized computed tomography (CT) scan, which is a rapid, non-contrast procedure that takes multiple cross-sectional images of the heart. Electrodes are placed on the chest to monitor the heart’s rhythm, ensuring images are taken between heartbeats to prevent blurring. This technique, called EKG gating, allows for clear visualization of the coronary arteries.
The scan is specifically looking for calcium deposits, which appear as bright white spots on the resulting images. Although calcium in the diet is beneficial, calcium found within the artery walls is a definitive marker of established atherosclerosis, or hardening of the arteries. This calcified plaque is a stable, mature form of the fatty deposits that build up over time, and its presence signals a higher lifetime risk of a cardiovascular event. The procedure requires no special preparation other than avoiding caffeine and smoking beforehand.
Who Should Get Screened and When
The cardiac calcium scan is generally not recommended for everyone, but rather for a specific group of asymptomatic individuals where the results can change a physician’s treatment recommendations. The test provides the most clinical value for adults typically aged 40 to 75 who fall into an “intermediate” risk category for cardiovascular disease. This intermediate risk is usually defined by a 10-year risk of 5% to 20% for an atherosclerotic cardiovascular disease (ASCVD) event, as calculated by risk assessment tools.
The scan is particularly useful for people who have risk enhancers such as a strong family history of premature heart disease or persistently elevated cholesterol levels. For patients with borderline high cholesterol who are hesitant about starting a statin medication, a CAC score can provide a definitive physical measure of risk to guide the shared decision-making process. A negative result can offer reassurance, while a positive result can motivate a patient to commit to aggressive lifestyle changes or preventive drug therapy.
Interpreting the Agatston Score
The final result of the CAC test is expressed as the Agatston score, a numerical value calculated by measuring the area and density of the detected calcium deposits. This score directly correlates with the total burden of calcified plaque. A score of zero is the most favorable result, indicating no detectable calcified plaque and suggesting a very low risk of a cardiac event over the next five to ten years.
A low score, ranging from 1 to 99, indicates minimal plaque and a mildly increased risk, which typically prompts a focus on lifestyle modifications. Scores between 100 and 399 represent moderate plaque burden and a moderate-to-high risk of an event, often leading to the initiation of preventive medication like statins. A score of 400 or higher signifies a large amount of plaque and extensive coronary artery disease, placing the individual at a high risk comparable to someone who has already experienced a cardiac event, warranting immediate and aggressive medical management.
Cost and Insurance Considerations
The financial consideration is a primary factor in deciding if the CAC test is “worth it,” as it is often not covered by standard health insurance plans or Medicare. Because the test is used for screening asymptomatic individuals, most insurers do not classify it as a medically necessary diagnostic procedure. The typical out-of-pocket cost for the test ranges from approximately $100 to $400, depending on the imaging center and geographic location.
Some facilities may offer discounted rates during specific health awareness campaigns, which can make the test more accessible. If a physician orders the test for a patient already experiencing symptoms or for a specific diagnostic purpose related to a known condition, insurance coverage may be possible, but this is less common. For individuals in the intermediate risk category, the relatively low cost is often viewed as a worthwhile investment for the definitive, actionable risk information it provides.