Importance  Current guidelines recommend a few different approaches to the use of coronary artery calcium (CAC) testing as a tool for risk assessment and decision-making regarding drug therapy for primary prevention of atherosclerotic cardiovascular disease (ASCVD).

Observations  Coronary artery calcium testing is not recommended for universal screening, particularly in patients at very low or high predicted risk for ASCVD, where its yield and utility for altering clinical decisions are limited. Use of CAC testing appears to be optimal when used in selected patients who are at intermediate or borderline risk of ASCVD as a sequential decision aid after initial quantitative risk assessment and consideration of individual patient risk-enhancing factors (eg, strong family history of premature ASCVD, chronic kidney disease). Although convincing clinical trials have not been completed, observational studies strongly suggest that, in those at intermediate risk, CAC testing can meaningfully reclassify risk and can support improved targeting of drug therapy to patients most likely to benefit.

Conclusions and Relevance  This narrative review summarizes the evidence available about the appropriate role of CAC testing for ASCVD risk assessment. Coronary artery calcium testing should be used selectively in patients who are at intermediate risk of ASCVD, when there is persistent uncertainty after performing standard risk assessment using traditional risk factors in a risk score, and after consideration of additional individual risk-enhancing factors. In these situations, the result of the CAC test can be helpful to clarify whether the patient’s true risk is high enough to justify initiation of primary prevention medications, such as statins or aspirin.