Understanding the Coronary Artery Calcium (CAC) Test
A coronary artery calcium (CAC) test, also known as a heart scan, is a quick and non-invasive procedure that uses a CT scan to measure the amount of calcified plaque in your coronary arteries. Plaque is a mixture of calcium, fat, and cholesterol that can accumulate on artery walls, potentially leading to a heart attack or stroke. The resulting Agatston score, a numerical value, helps doctors predict a patient's risk of a future cardiac event.
General Age Recommendations for a CAC Test
While there is no single mandated age for everyone to receive a CAC scan, medical consensus points to a specific demographic that stands to benefit most. The most relevant age group is typically adults between 40 and 75 who have an intermediate risk for heart disease based on traditional risk factors, but no clear symptoms. This window is when the test provides the most useful information for guiding preventive treatment decisions, such as whether to begin taking a statin.
For those younger than 40 with significant risk factors, such as a strong family history of early heart disease or a genetic predisposition like familial hypercholesterolemia, a doctor may recommend an earlier test. The decision should always be a conversation between the patient and a healthcare provider.
How Risk Factors Influence Timing
An individual's risk factors are a primary consideration for determining when to have a calcium score test. For example, a 2021 study funded by the National Heart, Lung, and Blood Institute (NHLBI) offered specific age guidance based on risk factors:
- Men with diabetes: Consider a first scan around age 37.
- Women with diabetes: An ideal time is around age 50.
- Men with traditional risk factors (smoking, high blood pressure, etc.): An ideal time is around age 42.
- Women with traditional risk factors: An ideal time is around age 58.
Other significant risk factors include obesity and an inactive lifestyle. The test helps stratify risk and decide if preventive measures are necessary.
When a CAC Test is Not Recommended
A CAC test is not a universal screening tool. It is generally not recommended for several groups of people:
- Already diagnosed with coronary artery disease (CAD): If a patient already has CAD, their treatment path is clear, and the test will not provide new information.
- Previously had a heart attack, bypass surgery, or stents: Similarly, this test offers no new insights for monitoring treatment effectiveness.
- High risk of heart disease with clear treatment path: If a doctor has already determined aggressive treatment is needed based on risk factors, the test is redundant.
- Low risk of heart disease with no symptoms: For people with minimal risk, the test is likely unnecessary.
- Pregnant women: Due to radiation exposure from the CT scan, the test is not recommended for pregnant women.
Calcium Score Test vs. Coronary CT Angiogram
| Feature | Coronary Artery Calcium (CAC) Test | Coronary CT Angiogram (CCTA) |
|---|---|---|
| Purpose | Screening for calcified plaque burden. | Diagnostic imaging for blockages, plaque volume, and plaque type (calcified and soft). |
| Invasiveness | Non-invasive, requires no contrast dye. | Non-invasive, but requires IV contrast dye injection. |
| Preparation | No special preparation required. | Requires an IV, and possibly medication to slow heart rate. |
| Cost | Typically lower cost; average is $100-$400. | More expensive, as it is a more comprehensive diagnostic tool. |
| Information | Measures calcified plaque and provides a risk score. Cannot see soft plaque. | Visualizes the arteries directly, detecting both calcified and soft plaque and showing any narrowing or blockages. |
| When to Use | For asymptomatic individuals with intermediate risk. | For symptomatic individuals, those with high risk, or to investigate a high CAC score. |
Interpreting Your Calcium Score
The numerical result from a CAC test, known as the Agatston score, helps determine your level of risk.
- Score of 0: Indicates no calcified plaque was detected, suggesting a low risk of a cardiac event in the next 2 to 5 years.
- Score of 1–100: Indicates mild plaque burden. This is considered low risk, but your doctor may recommend lifestyle changes.
- Score of 101–400: Suggests a moderate amount of plaque and a moderate to high risk. Further testing or treatment may be recommended.
- Score over 400: Points to extensive plaque buildup and a high risk of a heart attack.
Based on your score, your doctor can determine the best preventative strategy, which may include lifestyle changes, medication, or further diagnostic testing.
Conclusion
The age at which you should have a calcium score test is not a one-size-fits-all answer but depends on your overall cardiovascular risk profile. For adults aged 40 to 75 who are in the intermediate-risk category without symptoms, the test can provide valuable insight to guide preventative care. The decision to undergo a CAC scan is a conversation to have with your healthcare provider, weighing your personal risk factors against the benefits of the information gained. Armed with the knowledge from a CAC test, you and your doctor can develop a personalized plan to take charge of your heart health. For more on advanced cardiac diagnostics, the American Heart Association provides comprehensive resources on heart attack risk.
