Coronary Artery Calcium Testing—Too Early, Too Late, Too Often

Importance: Traditional risk factors, enhancing factors, and risk scores help clinicians assess atherosclerotic cardiovascular disease (ASCVD) risk for primary prevention. The latest cholesterol guidelines suggest measuring coronary artery calcium (CAC) score by computed tomography (CT) in those at intermediate risk when there is uncertainty about statin initiation for primary prevention. CAC testing can improve both risk estimation and adherence to cardiovascular risk-reducing behaviors. Observations: As measuring CAC score has become more widely available, this article focuses on 3 situations where CAC testing may be omitted or deferred until a time when CAC testing can provide clinically useful information. Three clinical scenarios to facilitate the clinician-patient risk discussion are as follows: (1) when CAC testing is too early, (2) when CAC testing is too late, and (3) when CAC testing is repeated too often. The timing of CAC testing sits within the decision point of lipid-lowering therapy use. High-risk young adults may face an elevated lifetime risk of cardiovascular disease despite a CAC level of 0, whereas older adults may not see an expected benefit over a short time horizon or may already be taking lipid-lowering therapy, rendering a CAC score less valuable. Integrating a CAC score into the decision to initiate lipid-lowering therapy requires understanding of a patient's risk factors, including age, as well as the natural history of atherosclerosis and related events. Conclusions and Relevance: These clinical scenarios reflect when consideration of CAC score is of use and when it is not. Although CAC testing is becoming more widely available and sought after by clinicians and patients alike, it is only as useful as the clinical context. Understanding when assessing CAC score is too early to effectively rule out risk, too late to influence decisions, or too often to yield clinically relevant information provides important insights that optimize the clinical utility of this potentially valuable prognostic tool.