From the Guidelines
Coronary Artery Calcium (CAC) scoring scans have a high sensitivity of 98% and a moderate specificity of 40% for detecting significant coronary artery disease (CAD) on invasive coronary angiography. When considering the diagnosis of coronary artery disease and myocardial ischemia, it's crucial to understand the strengths and limitations of CAC scoring. The high sensitivity of CAC scoring makes it a valuable tool for ruling out CAD in symptomatic patients, as a zero CAC score is associated with a low likelihood of obstructive CAD 1. However, the moderate specificity means that a nonzero CAC score does not necessarily confirm the presence of significant CAD.
Some key points to consider when interpreting CAC scores include:
- The presence of a nonzero CAC score has a high sensitivity for detecting significant CAD, but the specificity is lower, which can lead to false positives 1.
- A CAC score of zero is associated with a low risk of obstructive CAD, but it does not completely rule out the possibility of non-calcified plaque or mild CAD 1.
- The diagnostic accuracy of CAC scoring can be influenced by patient age, with younger patients more likely to have non-calcified plaque and false negative results 1.
In clinical practice, CAC scoring is most useful as a risk stratification tool in asymptomatic patients with intermediate cardiovascular risk, helping physicians determine the need for preventive therapies or further cardiac testing 1. For symptomatic patients, CAC scoring can be used to help rule out obstructive CAD, but it should be interpreted in conjunction with other diagnostic tests and clinical evaluation 1.
From the Research
Accuracy of Coronary Artery Calcium Scoring
- The accuracy of Coronary Artery Calcium (CAC) scoring scans in detecting coronary artery disease (CAD) and myocardial ischemia has been evaluated in several studies 2, 3, 4, 5, 6.
- A study published in 2010 found that CAC scoring had a sensitivity of 79-80% and specificity of 95-98% in detecting coronary anomalies 3.
- Another study published in 2005 found that CAC scoring had a sensitivity of 29% and specificity of 95% in demonstrating stenosed segments, while CT angiography had a sensitivity of 79% and specificity of 95% 4.
- A study published in 2005 also found that the combination of CAC scoring and CT angiography improved the sensitivity of CT angiography in demonstrating significant coronary disease in patients, without a loss of specificity 4.
- A more recent study published in 2023 found that incorporating CAC scoring in the prediction of obstructive CAD with myocardial ischemia improved the accuracy of the model, with an area under the receiver-operating characteristic curve (AUC) of 0.83 6.
Specificity and Sensitivity of CAC Scoring
- The specificity of CAC scoring in detecting coronary artery disease and myocardial ischemia has been reported to be high, ranging from 95-98% 3, 4.
- The sensitivity of CAC scoring has been reported to be lower, ranging from 29-80% 3, 4.
- The sensitivity and specificity of CAC scoring can vary depending on the threshold used and the population being studied 4, 5.
Clinical Applications of CAC Scoring
- CAC scoring can be used as a non-invasive test to detect coronary artery disease and myocardial ischemia 2, 3, 4, 5, 6.
- The results of CAC scoring can be used to guide clinical decision-making, such as the need for further testing or treatment 2, 5, 6.
- CAC scoring can also be used to monitor the progression of coronary artery disease over time 2.