Coronary Calcium Score (CAC)

A coronary calcium score (CAC) is a non-invasive measurement that quantifies the amount of calcium buildup in your coronary arteries - the blood vessels that supply oxygen and nutrients to your heart muscle [1]. Also known as a coronary artery calcium test, heart CT calcium scan, or CAC test, this specialized imaging assessment serves as a powerful biomarker for cardiovascular health [1].

The calcium deposits measured in this test form as part of atherosclerotic plaques that develop over time in your coronary arteries [1]. When plaques containing cholesterol, fats, and other substances accumulate in arterial walls, they can become calcified - essentially hardened with calcium deposits [1]. This calcification process occurs slowly over years, often long before any symptoms of coronary artery disease become apparent [1].

The relationship between coronary calcium and heart disease risk is straightforward: more calcium typically indicates more plaque burden and a higher likelihood of significant coronary artery disease [2]. This makes the coronary calcium score an invaluable tool for early detection and risk stratification, as it can identify individuals at risk for heart attacks before they experience any symptoms [1].

Unlike traditional risk assessment methods that rely solely on clinical factors like blood pressure and cholesterol levels, the coronary calcium score provides direct visualization of atherosclerotic disease in your coronary arteries, offering a more precise picture of your cardiovascular health status [2].

The coronary calcium score stands out as one of the strongest predictors of future heart attacks and cardiovascular events, making it a crucial tool in preventive cardiology [2]. Research has demonstrated that incorporating CAC scores into risk assessment significantly improves the accuracy of predicting 10-year coronary heart disease risk, including heart attacks, cardiac arrest, confirmed angina requiring revascularization, and cardiac death [2].

This measurement is particularly valuable for identifying asymptomatic individuals who may be at higher risk for coronary artery disease than traditional risk factors would suggest [1]. The MESA CHD Risk Score, which incorporates coronary calcium scoring, enables clinicians to calculate risk both before and after inclusion of an individual's CAC score, providing a more comprehensive risk assessment [2].

The coronary calcium score serves as a powerful clinical decision-making tool that guides preventive treatments and medication recommendations [1]. When your score indicates elevated risk, healthcare providers can make more informed decisions about initiating statin therapy, blood pressure medications, or other preventive interventions that might not have been considered based on traditional risk factors alone [2].

Perhaps most importantly, the coronary calcium score often serves as a motivational tool for patients. The Coronary Age calculator, which transforms the MESA 10-year CHD Risk Score into an easily understood age equivalent, helps patients better appreciate their cardiovascular risk [2]. For example, a 55-year-old patient might learn they have the equivalent heart disease risk of a healthy 78-year-old, which can be a powerful motivator for lifestyle changes and treatment adherence [2].

This concrete visualization of heart disease risk frequently leads to improved patient compliance with medications, dietary changes, and exercise recommendations, as individuals can better understand the tangible benefits of these interventions for their long-term health [2].

A coronary calcium score is obtained through a specialized computed tomography (CT) scan that uses advanced cardiac CT scanners specifically designed for heart imaging [1]. This non-invasive procedure captures detailed images of your coronary arteries using a series of X-rays to detect and quantify calcium deposits within atherosclerotic plaques [1].

The gold standard for calculating coronary calcium scores is the Agatston scoring method, which takes into account both the area and density of calcium deposits found in your coronary arteries [4]. This standardized approach ensures consistent and comparable results across different imaging centers and healthcare providers.

One of the significant advantages of coronary calcium scoring is that it requires no contrast dye injection, unlike many other cardiac imaging procedures [1]. The scan uses low-dose radiation exposure, making it a relatively safe diagnostic tool when clinically appropriate [1]. Most coronary calcium scans can be completed in 10-15 minutes with minimal preparation required from the patient [1].

During the procedure, you'll lie on a table that slides into the CT scanner while the machine takes multiple images of your heart from different angles. You may be asked to hold your breath briefly during image acquisition to ensure clear, high-quality pictures of your coronary arteries [1].

The images are then interpreted by trained radiologists or cardiologists who identify areas of calcification and calculate your total coronary calcium score [1]. This interpretation requires specialized expertise to accurately distinguish calcium deposits from other structures and to ensure precise quantification of the calcified plaque burden in your coronary arteries.