February 1, 2024

What is a Coronary Artery Calcium (CAC) score?

A Coronary Artery Calcium (CAC) score, also known as a calcium score or coronary calcium scan, is a medical test used to assess the amount of calcium deposits in the coronary arteries of the heart. These deposits are often associated with atherosclerosis, a condition where the arteries become narrowed and hardened due to the buildup of plaque, which is primarily composed of cholesterol and calcium.

Here's how the test typically works:

  1. Imaging: The patient undergoes a computed tomography (CT) scan, which uses X-rays to create detailed images of the heart and its surrounding blood vessels.
  2. Calcium measurement: During the CT scan, the amount of calcium in the coronary arteries is quantified. The presence of calcium deposits is a sign of atherosclerosis.
  3. Scoring: The results are then used to calculate a CAC score, which represents the amount of calcified plaque in the coronary arteries. A higher CAC score indicates a greater amount of calcified plaque and a higher risk of coronary artery disease.

The interpretation of a good Coronary Artery Calcium (CAC) score can vary depending on age and other individual risk factors. Generally, a lower CAC score is considered better, as it suggests a lower burden of coronary artery calcium and, by extension, a lower risk of coronary artery disease. However, what constitutes a "good" CAC score can differ based on age and should be assessed in the context of other risk factors.

Here are some general guidelines for CAC scores by age, but please keep in mind that these are not strict cutoffs and should be discussed with a healthcare provider:

  1. Younger individuals (under 40):
    - CAC score of 0: This is considered very low risk, indicating little to no coronary artery calcium.
    - Low scores (1-10): Still generally low risk, but risk assessment should consider other factors.
  2. Middle-aged individuals (40-60):
    - CAC score of 0: Still considered very low risk.
    - Low scores (1-10 or 11-100): Low to moderate risk, depending on other risk factors.
    - Intermediate scores (101-400): Moderate risk.
    - High scores (over 400): Higher risk.
  3. Older individuals (over 60):
    - CAC score of 0: Low risk.
    - Low scores (1-10 or 11-100): Moderate risk.
    - Intermediate scores (101-400): Moderate to high risk.
    - High scores (over 400): High risk.

The CAC score is used to help assess an individual's risk of heart disease and is often used in conjunction with other risk factors such as age, sex, family history, blood pressure, cholesterol levels, and smoking history. It can provide additional information to guide treatment decisions and preventive strategies. A high CAC score may prompt further evaluation and management, while a low or zero score may suggest a lower risk of heart disease.