What is the accuracy of a coronary calcium scan (Coronary Artery Calcium scan) in detecting coronary artery disease?

From the Guidelines

Coronary calcium scans are highly accurate for detecting calcified plaque in coronary arteries, with a high negative predictive value for the exclusion of obstructive CAD, as demonstrated in a large multicenter study, the PROMISE trial 1. The test uses specialized CT scanning to measure calcium deposits in coronary arteries, producing a calcium score that correlates with atherosclerosis severity.

• A score of zero indicates very low cardiovascular risk (less than 1% annual event rate),
• while scores above 400 suggest significant coronary artery disease requiring further evaluation, as shown in a study by Mitchell et al 1. The scan's accuracy is particularly strong for identifying patients at intermediate risk who might benefit from preventive therapies. However, the test has limitations - it cannot detect non-calcified soft plaque, may miss early disease in younger patients, and exposes patients to a small radiation dose (equivalent to about 1-2 chest X-rays), as noted in the CORE-64 study 1. For optimal accuracy, patients should remain still during the brief 10-15 minute procedure and follow breathing instructions carefully, as the CCTA ACCURACY trial found 95% sensitivity and 83% specificity for detection of CAD 1. The test requires no special preparation, though avoiding caffeine beforehand may help maintain a steady heart rate for clearer images.
• The diagnostic performance of CCTA was not influenced by angina pectoris type, as shown in a meta-analysis by Haase et al 1.
• A meta-analysis to evaluate the diagnostic accuracy of 64-slice CCTA compared with conventional selective coronary angiography in symptomatic patients with suspected CAD found that the sensitivity, specificity, PPV, and NPV were 86%, 96%, 83%, and 96.5%, respectively, by per-segment analysis and 97.5%, 91%, 93%, and 96.5%, respectively, by per-patient analysis 1. The high accuracy of coronary calcium scans makes them a valuable tool for detecting calcified plaque in coronary arteries and assessing cardiovascular risk, as demonstrated in the MESA study 1.

From the Research

Calcium Scan Accuracy

• The accuracy of calcium scans in assessing the severity of atherosclerosis is well-established, with studies showing that coronary artery calcium scanning is a reliable test for quantifying calcium deposition in the coronary arteries 2, 3.
• The Agatston score, which is used to quantify calcium deposition, is a strong predictor of cardiovascular risk, with higher scores indicating a greater risk of cardiovascular events 2, 4.
• The accuracy of calcium scans is also influenced by factors such as age, sex, and race, with females tend to have lower scores than males at any given age 2.
• The presence and extent of coronary calcification provide direct evidence of the presence and extent of coronary artery disease, and CAC predicts future events independently of concomitant conventional cardiovascular risk factors 5.
• Technical advances such as photon counting detectors and combination with nuclear approaches (eg, NaF imaging) promise to improve the performance of cardiac computed tomography and provide noninvasively specific and clinically actionable information 5.

Interpretation of Calcium Scan Results

• The interpretation of calcium scan results is critical, with a score of 0 indicating that a cardiovascular event is extremely unlikely in the next 5 years, while a score greater than 0 portends a coronary event 2.
• The number of vessels with CAC, the presence of CAC in the left main coronary artery, and specific highlighting of individuals with very high CAC scores of greater than 1000 are important points to report when interpreting CAC scans 3.
• The 10-year coronary heart disease risk can also be easily assessed using the free online Multi-Ethnic Study of Atherosclerosis risk score calculator when risk factor information is available 3.

Clinical Implications

• Calcium scans have important clinical implications, with aggressive treatment warranted for individuals with elevated calcium scores, including significant lifestyle changes and medications to reduce low-density lipoprotein cholesterol 2.
• The use of CAC testing in shared decision making between the clinician and patient is recommended, with several guidelines supporting its use in cardiovascular risk stratification and preventive treatment of asymptomatic patients with unclear cardiovascular disease risk 3, 4.