From the Guidelines
Cardiac CT calcium scoring is the preferred initial test for asymptomatic patients with intermediate risk factors, while cardiac CT angiography is preferred for symptomatic patients with suspected coronary artery disease. When deciding between cardiac CT calcium scoring and cardiac CT angiography, it's essential to consider the clinical context and the purpose of the test. Cardiac CT calcium scoring is a non-contrast, low-radiation test that quantifies calcified plaque in coronary arteries, providing a numerical score that correlates with atherosclerotic burden and future cardiovascular risk 1. This test is most useful for asymptomatic patients with intermediate risk factors to guide preventive therapy decisions. On the other hand, cardiac CT angiography is a more comprehensive test that uses contrast dye to visualize the coronary artery lumen and detect both calcified and non-calcified plaque, providing detailed information about stenosis severity, plaque characteristics, and cardiac anatomy 1.
Some key points to consider when choosing between these tests include:
- The patient's symptoms and risk factors: asymptomatic patients with intermediate risk factors may benefit from calcium scoring, while symptomatic patients with suspected coronary artery disease may require CT angiography 1.
- The need for detailed anatomical assessment: CT angiography is preferred when detailed information about stenosis severity, plaque characteristics, and cardiac anatomy is needed 1.
- The patient's kidney function: CT angiography requires intravenous contrast, which is contraindicated in patients with kidney disease 1.
- The patient's heart rate: CT angiography necessitates heart rate control with beta-blockers 1.
In terms of diagnostic accuracy, cardiac CT angiography has a high negative predictive value for obstructive coronary disease, but its accuracy can be reduced by extensive coronary calcification and high body mass index 1. Cardiac CT calcium scoring, on the other hand, has a high sensitivity for detecting significant coronary stenosis, but its specificity is lower 1.
Overall, the choice between cardiac CT calcium scoring and cardiac CT angiography depends on the clinical question and the patient's individual characteristics. In general, cardiac CT calcium scoring is the preferred initial test for asymptomatic patients with intermediate risk factors, while cardiac CT angiography is preferred for symptomatic patients with suspected coronary artery disease 1.
From the Research
Cardiac CT Calcium Score vs Cardiac CT Angiogram
- The cardiac CT calcium score and cardiac CT angiogram are both used to evaluate suspected coronary artery disease (CAD) [ 2, 3].
- A study published in 2023 found that a coronary artery calcium (CAC) score of 0 had a high negative predictive value (NPV) for obstructive CAD, but the sensitivity was lower in patients under 45 years of age [ 2].
- The same study suggested that CAC testing can be used as a gatekeeper to further cardiac testing, but a full CCTA may be needed for safely ruling out obstructive CAD in the youngest patients [ 2].
Comparison of Diagnostic Tools
- A review published in 2015 compared cardiac CT vs. stress testing in patients with suspected CAD, and found that cardiac CT angiography technology allows for noninvasive visualization of coronary artery disease [ 3].
- Another study published in 2012 found that coronary CT angiography (CTA) has incremental value over routine risk factors for predicting major adverse cardiac events (MACE), and is superior to CAC scoring [ 4].
Clinical Utility and Safety
- A randomized trial published in 2016 found that a tiered cardiac CT protocol, including a calcium scan followed by CT angiography, was an effective and safe alternative to functional testing for patients with suspected stable CAD [ 5].
- The trial also found that the cardiac CT protocol resulted in lower cumulative diagnostic costs and radiation exposure [ 5].
- A review published in 2015 highlighted the role of CAC scoring and coronary CTA in detecting coronary plaque and impacting patient prognosis and management [ 6].