Calcium plays a vital role in several bodily functions. However, it can cause a buildup of plaque in the arteries, which may eventually cause a blockage. A coronary artery calcium (CAC) score shows the level of calcium in the arteries.

Cholesterol can also lead to the formation of plaque, which can build up and cause a full or partial blockage of the arteries.

A doctor may order a test to check a person’s CAC levels and assess the risk of heart disease. They may refer to a CAC test in various ways:

  • cardiac CT for calcium scoring
  • calcium scan of the heart
  • calcium scan test
  • cardiac scoring
  • coronary calcium score

A CAC test involves using a CT scan to examine the arteries and blood vessels leading into the heart to check for the presence of calcified plaque. It does not test for or show blockages.

Studies have shown that a CAC score can show an estimate of a person’s arterial age, thereby indicating their cardiovascular risk. A person’s baseline score may change with age. When their actual age and arterial age line up, they fall within the expected score range.

Although CAC scoring may be helpful for determining a person’s risk of heart disease, allowing those at higher risk to start preventive medications, the scoring is not necessary or recommended for everyone. A person should talk with a doctor about whether they recommend a person undergo testing to get a CAC score.

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CAC and cholesterol levels are both risk factors for a person developing heart disease.

Both CAC and cholesterol can contribute to the buildup of plaque in the arteries. Over time, this substance causes the artery walls to thicken and restrict blood flow. This process is known as atherosclerosis.

When the arteries can no longer carry enough blood through the body, there may be a lack of oxygen and other nutrients reaching vital organs and tissues. As a result, a person may have a heart attack or stroke.

Having both a high CAC score and high cholesterol levels could increase a person’s risk of developing heart disease, but having one high score does not necessarily mean that a person will have a high score for the other. In fact, a person can have high cholesterol and a zero CAC score.

When both scores are high, a doctor may recommend taking statins to help lower cholesterol levels. A person will likely need to take the medication as a preventive measure for the rest of their life.

In general, a high cholesterol score — generally a score of ≥190 milligrams per deciliter of low-density lipoprotein cholesterol (LDL-C) — alongside a zero CAC score indicates a low risk of coronary heart disease.

In a 2019 study, researchers challenged the notion that having a high LDL-C is independently a risk factor for heart disease and cardiac events. They found that a CAC score of zero, along with a few other factors, puts people living with high LDL-C scores in a low risk group for cardiac events.

The other associated factors the researchers noted included:

  • absence of diabetes
  • younger age
  • assigned female at birth

A person living with high levels of cholesterol could still have a CAC score of zero. In most cases, a person who receives a score of zero has a reduced risk of developing heart disease.

The American College of Cardiology Foundation’s (ACCF’s) 2018 guidelines indicate that a person who receives a zero CAC score does not need to take statins immediately. They only advise those with a zero CAC score to take statins if they:

  • smoke
  • have diabetes
  • have a family history of coronary artery disease

What does a zero score mean?

A CAC score of zero means that the CT scan of the heart did not reveal a buildup of calcified plaque in the blood vessels leading into the heart. As a result, the person has a low risk of developing heart disease or experiencing cardiovascular events such as a heart attack.

Do I need statins if my calcium score is zero?

The American Heart Association (AHA) and several studies have concluded that a CAC score of zero means a person can typically avoid taking statins for cholesterol. People with a score of zero have a low risk of developing heart disease.

Studies have shown that a person’s CAC score can predict their risk of developing coronary heart disease and provide a general estimate of their arterial age.

A person’s CAC levels will increase as they age, but the expected range will also change based on their actual age. Ideally, a person’s actual age and arterial age will correspond.

The following table shows a breakdown of a person’s average arterial age based on their CAC score:

CACArterial age in years CACArterial age in years
039 (range 32–46)10073 (range 71–74)
1056 (range 53–60)20078 (range 75–80)
2061 (range 59–63)30080 (range 78–83)
3064 (range 62–66)40083 (range 79–86)
4066 (range 65–67)50084 (range 80–88)
5068 (range 67–69)75087 (range 83–92)
6069 (range 68–70)1,00089 (range 84–94)
7070 (range 69–71)1,50092 (range 87–98)
8071 (range 70–72)2,00094 (range 88–100)
9072 (range 71–73)2,50096 (range 89–102)

The closer a person’s actual age is to their estimated arterial age, the more likely they are to fall within the expected range. For example, if a 56-year-old person has a CAC score of 10, they would fall within this range because their actual age and estimated age are similar.

In contrast, a 40-year-old person with a CAC score of 10 has an elevated score because their actual age and estimated arterial age differ. In general, the higher the score, the more at risk the person is of developing coronary heart disease.

What to do if the results are high?

A person should talk with a doctor about their score. People with a score higher than 100 will likely need to take statins to help lower their cholesterol levels.

However, a doctor may not immediately prescribe statins for people with a score between 1 and 99.

If a person has a high cholesterol score and a zero CAC score, a doctor will likely recommend no further medical action. Studies have shown that a person in these cases has a lower risk of developing heart disease.

A doctor may still recommend that a person eat a nutritious diet, get regular exercise, and avoid smoking or drinking.

Statins

Statins are a type of cholesterol-lowering medication that can also help protect the heart. The ACCF notes that statins can benefit health by:

  • reducing the risk of the arteries hardening
  • preventing strokes and heart attacks
  • helping prevent death due to heart disease

Statins help prevent the liver from creating LDL cholesterol and may reduce cholesterol levels by as much as 50%. They can also help prevent plaque from breaking apart and forming clots that can cause heart attacks and stroke.

In addition to taking statins, a person should work with their doctor to develop an eating and exercise plan that will help them reduce their heart disease risk.

Not everyone needs a CAC screening. The AHA typically recommends the testing for people between the ages of 40 and 75 years. A doctor may recommend a CAC test if a younger person has an elevated cholesterol level.

CAC scoring is not the only diagnostic test that doctors can use to assess a person’s risk of heart disease. They will likely order other tests, such as:

According to the Centers for Disease Control and Prevention (CDC), a person will likely not experience any symptoms of clogged arteries until they have a heart attack. Signs of a heart attack include:

  • discomfort or pain in the chest
  • shortness of breath
  • discomfort or pain in the arms or shoulders
  • nausea, weakness, lightheadedness, or cold sweats

A person should seek immediate medical attention if they experience any of the above symptoms.

A person can have a high cholesterol score and a zero CAC score. When this occurs, doctors generally agree that a person’s overall coronary heart disease risk is low and that the person does not require medical intervention.

A person with an elevated score will likely benefit from taking statins to help reduce their cholesterol numbers. A person should work with a doctor to determine the best course of action once a CAC score comes back.