Coronary artery calcium scoring: Its practicality and clinical utility in primary care
ABSTRACT
Coronary artery calcium scoring is useful as a risk-stratification tool in coronary artery disease, and it outperforms other risk-assessment methods. American College of Cardiology/American Heart Association guidelines give the test a IIB recommendation in clinical scenarios in which risk stratification is uncertain. However, if the test is not used in the appropriate clinical setting, misinterpretation of the results can lead to unnecessary cardiac testing. This review provides the primary care provider with basic knowledge about the test’s clinical utility, interpretation, risks, and limitations.
KEY POINTS
- Coronary artery calcium testing is useful in diagnosing subclinical coronary artery disease and in predicting the risk of future cardiovascular events and death.
- Given the high negative predictive value of the test, it can also serve to reclassify risk in patients beyond traditional risk factors.
- Along with shared decision-making, elevated calcium scores can guide the initiation of statin or aspirin therapy.
- A high score in an asymptomatic patient should not trigger further testing without a comprehensive discussion of the risks and benefits.
Example 1
A 55-year-old man presents for an annual physical and is found to have a 10-year risk of atherosclerotic cardiovascular disease of 7%, placing him in the intermediate-risk category. Despite an extensive conversation about lifestyle modifications and pharmacologic therapy, he is reluctant to initiate these measures. He is otherwise asymptomatic. Would calcium scoring be reasonable?
Yes, it would be reasonable to perform coronary artery calcium scoring in an otherwise asymptomatic man to help reclassify his risk for a coronary vascular event. The objective data provided by the test could motivate the patient to undertake primary prevention efforts or, if his score is 0, to show that he may not need drug therapy.
Example 2
A 55-year-old man who has a family history of coronary artery disease, is an active smoker, and has diabetes mellitus presents to the clinic with 2 months of exertional chest pain that resolves with rest. Would coronary artery calcium scoring be reasonable?
This patient is symptomatic and is at high risk of coronary artery disease. Statin therapy is already indicated in the AHA/ACC guidelines, since he has diabetes. Therefore, calcium scoring would not be helpful, as it would not change this patient’s management. Instead, he would be best served by stress testing or coronary angiography based on the stability of his symptoms and cardiac biomarkers.
Example 3
A 30-year-old woman with no medical history presents with on-and-off chest pain at both exertion and rest. Her electrocardiogram is unremarkable, and cardiac enzyme tests are negative. Would coronary calcium scoring be reasonable?
This young patient’s story is not typical for coronary artery disease. Therefore, she has a low pretest probability of obstructive coronary artery disease. Moreover, calcium scoring may not be helpful because at her young age there has not been enough time for calcification to develop (median age is the fifth decade of life). Thus, she would be exposed to radiation unnecessarily at a young age.
What to do with an elevated calcium score?
Coronary artery calcification is now being incidentally detected as patients undergo CT for other reasons such as screening for lung cancer based on the US Preventive Services Task Force guidelines. Patients may also get the test done on their own and then present to a provider with an elevated score.
It is important to consider the entire clinical scenario in such patients and not just the score. If a patient presents with an elevated calcium score but has no symptoms and falls in the intermediate-risk group, there is evidence to suggest that he or she should be started on statin or aspirin therapy or both.
As mentioned above, an abnormal test result does not mean that the patient should undergo more-invasive testing such as cardiac catheterization or even stress testing, especially if he or she has no symptoms. However, if the patient is symptomatic, then further cardiac evaluation would be recommended.
SUMMARY
Measuring coronary artery calcium has been found to be valuable in detecting coronary artery disease and in predicting cardiovascular events and death. The test is relatively easy to perform, with newer technology allowing for less radiation and cost. It serves as a more personalized measure of disease and can help facilitate patient-physician discussions about starting pharmacologic therapy, especially if a patient is reluctant.
Currently, coronary calcium scoring has a class IIB recommendation in scenarios in which the risk-based treatment decision is uncertain after formal risk estimation has been done according to the ACC/AHA guideline. The Society of Cardiovascular Computed Tomography guideline and expert consensus documents are more specific in recommending the test in asymptomatic patients in the intermediate-risk group.
Limitations of calcium scoring include the possibility of unnecessary cardiovascular testing such as cardiac catheterization or stress testing being driven by the calcium score alone, as well as the impact of incidental findings. With increased reporting of the coronary calcium score in patients undergoing CT for lung cancer screening, the score should be interpreted in view of the entire clinical scenario.
