From the Guidelines
Yes, a patient can have a coronary artery calcium (CAC) score of 0 while still having carotid stenosis. These two conditions represent atherosclerotic disease in different vascular territories and can develop independently. A CAC score of 0 indicates no detectable calcified plaque in the coronary arteries, suggesting low coronary risk, but it does not rule out atherosclerosis in other vascular beds like the carotid arteries, as noted in a study published in the Journal of Internal Medicine 1. Carotid stenosis is caused by plaque buildup in the carotid arteries that supply blood to the brain, while the CAC score specifically evaluates the coronary arteries that supply the heart.
Key Considerations
- Risk factors such as hypertension, smoking, diabetes, and dyslipidemia can affect different vascular territories to varying degrees.
- Carotid plaque may be non-calcified or develop earlier than coronary calcification in some patients.
- Comprehensive cardiovascular risk assessment should include evaluation of multiple vascular territories rather than relying on a single test, as emphasized by guidelines from the American College of Cardiology/American Heart Association 1.
- Patients with carotid stenosis but a CAC score of 0 still require appropriate management of their carotid disease and cardiovascular risk factors.
Management Implications
- A CAC score of 0 identifies individuals at lower risk of ASCVD events and death over a >10-year period, but does not negate the need for managing carotid stenosis and other cardiovascular risk factors.
- Clinical judgment about risk should prevail, considering the absence of coronary artery calcium does not rule out non-calcified plaque.
- The use of coronary artery calcium measurement can be a useful tool in refining risk assessment for preventive interventions, such as statin therapy, especially in individuals with intermediate predicted risk, as suggested by the 2019 ACC/AHA guideline on the primary prevention of cardiovascular disease 1.
From the Research
Carotid Stenosis and CAC Score
- A patient can have a Coronary Artery Calcium (CAC) score of 0 and still have carotid stenosis, as these two conditions are related but distinct measures of cardiovascular health 2.
- The presence of carotid plaque is a marker of increased risk, and its association with cardiovascular risk and incident CAC in people without CAC is an area of ongoing research 2.
- Studies have shown that carotid plaque presence and plaque score are independently associated with coronary heart disease risk and incident CAC among middle-aged asymptomatic individuals with an initial CAC score of 0 2.
Relationship Between CAC Score and Carotid Plaque
- The Multi-Ethnic Study of Atherosclerosis found that carotid plaque score was a weaker predictor of cardiovascular disease events compared to CAC score 3.
- CAC score was a stronger predictor of coronary heart disease events, while carotid plaque score was a weaker predictor of stroke/transient ischemic attack events 3.
- The use of CAC scoring was associated with significant improvements in the reclassification and discrimination of incident cardiovascular disease 4.
Carotid Artery Calcium Score
- A new method for quantifying carotid artery calcium has been proposed, which involves calculating the total weight value of voxels with a Hounsfield Unit value ≥130 5.
- This method, known as the Carotid Artery Calcium Score (CACS), has been tested in a pilot study and shows promise for risk stratification of cerebrovascular events 5.
- Further studies are needed to verify the potential utility of CACS for predicting cardiovascular risk 5.
Clinical Implications
- CAC scoring has emerged as a widely available and consistent means of assessing risk for major cardiovascular outcomes, especially in asymptomatic people 6.
- CAC testing in asymptomatic populations is cost-effective across a broad range of baseline risk 6.
- The presence of carotid stenosis in a patient with a CAC score of 0 highlights the importance of considering multiple factors when assessing cardiovascular risk 2, 4, 3.