Coronary artery calcium scoring. What clinicians need to know

Coronary artery calcium (CAC) scoring, measured by computed tomography (CT), quantifies calcified coronary plaque and reflects the burden of coronary atherosclerosis. The Agatston score, calculated based on lesion density and area, stratifies patients into risk categories: a score of 0 indicates no detectable calcification, 1-99 suggests mild plaque, 100-399 indicates moderate burden, and scores of 400 or more reflect high to extensive calcification, with scores above 1000 indicate extremely high atherosclerotic burden. CAC scoring is most beneficial in asymptomatic adults aged 40 to 75 years with borderline (5-7.5%) or intermediate (7.5-20%) 10-year ASCVD risk when uncertainty exists regarding statin initiation. The Multi-Ethnic Study of Atherosclerosis (MESA) found that a CAC score of 0 significantly reduces estimated ASCVD risk compared to pooled cohort equation (PCE) predictions, with observed event rates of approximately 1.5% for borderline-risk and 4.5% for intermediate-risk individuals, supporting reclassification into a lower-risk category. Scores of 1-99 represent modestly elevated risk and may guide prevention based on clinical judgment and patient preference. Scores from 100 to 400 reflect moderate plaque burden and support statin therapy, while high scores above 400 reflect substantial atherosclerotic burden, mandating aggressive preventive interventions. CAC testing is generally not indicated in younger, low-risk adults, as they may develop ASCVD later in life, and a score of 0 could lead to false reassurance that discourages appropriate prevention. Similarly, testing is typically unnecessary in elderly individuals with established atherosclerotic disease, as results rarely change management. It is also not recommended in those with clear statin indications, including patients with diabetes, familial hyperlipidemia, existing ASCVD, or those already on lipid-lowering treatment. Frequent CAC retesting is discouraged due to limited clinical benefit, unnecessary costs, potential downstream testing, patient anxiety, and exposure to radiation, though repeating CAC after five years may be reasonable for those initially scoring zero. The recent CAUGHT-CAD trial showed that CAC-informed strategies reduced LDL cholesterol and slowed plaque progression in intermediate-risk individuals with familial coronary artery disease, highlighting its importance. Future research should focus on optimizing CAC use to enhance patient outcomes while balancing clinical utility, cost, and risk.