Coronary Artery Calcium (CAC) is pathognomonic for coronary atherosclerosis. Calcium deposition occurs in the advanced stages of plaque development, and the amount of calcified plaque roughly correlates with the total atherosclerotic plaque burden — representing approximately 20% of the total plaque volume.
1 How it's measured
CAC is detected using a non-contrast, ECG-gated CT scan with 3 mm slice thickness. Because calcium is highly dense, no contrast administration is needed for visualization. A single, short, low-dose scan is enough.
2 Why it matters
The presence and extent of CAC strongly correlate with the risk of future cardiovascular events and all-cause mortality in asymptomatic individuals. CAC testing is a powerful, non-invasive biomarker that provides incremental risk stratification beyond traditional cardiovascular risk factors — which is why it routinely changes management when traditional calculators land a patient in the borderline-to-intermediate band.