When to use Coronary Artery Calcium (CAC) scores?

From the Guidelines

Coronary calcium scores should be used in individuals with intermediate predicted risk (≥7.5% to <20%) to refine risk assessment for preventive interventions, such as statin therapy, as recommended by the 2019 ACC/AHA guideline 1. When deciding whether to use coronary calcium scores, it is essential to consider the patient's risk profile. The scores are most useful for individuals at intermediate risk for cardiovascular disease, typically those with a 5-20% 10-year risk of cardiovascular events based on traditional risk factors.

• This test is particularly valuable when there is uncertainty about whether to start statin therapy or other preventive measures.
• The calcium score helps reclassify risk by detecting calcified plaque in coronary arteries, with scores above 100 indicating elevated risk and scores above 300 suggesting significant atherosclerotic burden.
• A coronary artery calcium score of zero identifies individuals at lower risk of ASCVD events and death over a >10-year period, who appear to derive little or no benefit from statins for ASCVD risk reduction 1. The test is not recommended for low-risk individuals (young people without risk factors) or those already known to be at high risk (established coronary artery disease, diabetes with target organ damage, or multiple risk factors).
• It's also not useful for monitoring treatment effects, as calcium scores typically increase over time even with effective therapy.
• The radiation exposure is relatively low (about 1 mSv), making it a reasonable one-time test for risk stratification.
• Before ordering, consider that abnormal results may lead to additional testing, and insurance coverage varies. According to the 2023 JACC: Cardiovascular Imaging guideline, if the risk decision is uncertain, consider measuring CAC in selected adults, with CAC = zero lowering risk, CAC = 1-99 favoring statin, and CAC = 100+ and/or ≥75th percentile requiring initiation of statin therapy 1.
• The test provides valuable information about subclinical atherosclerosis that can guide preventive therapy decisions and potentially improve patient motivation for lifestyle changes and medication adherence.
• Recent guidelines, including the 2023 major global coronary artery calcium guidelines, recommend CAC as an absolute risk stratifier for both cholesterol management and primary ASCVD prevention in intermediate-risk patients 1.

From the Research

Coronary Calcium Scores: When to Use

• Coronary calcium scores can be used to guide shared decision making in intermediate-risk patients to inform the risk discussion for initiating or intensifying statin therapy 2
• The decision to use coronary calcium scores is uncertain across a broad range of estimated 10-year ASCVD risk of 5% to 20%, and coronary artery calcium testing can reclassify risk upward or downward in approximately 50% of this group 2
• Coronary calcium scores can be used to identify individuals at increased atherosclerotic cardiovascular disease (ASCVD) risk and to inform the decision to initiate aspirin therapy in primary prevention 3

Patient Selection

• Coronary calcium scores are particularly useful in patients with intermediate or high estimated 10-year risk using traditional population-based risk calculators 4
• Patients with statin-associated muscle symptoms may benefit from coronary calcium scoring to individualize estimated risk and identify those most likely to benefit from statin therapy 4
• Coronary calcium scores can be used in symptomatic patients undergoing positron emission tomography-stress testing to predict the need for revascularization and incident major adverse coronary events (MACE) 5

Risk Assessment

• Coronary calcium scores can improve risk discrimination when added to the Pooled Cohort Equations (PCE) or the MESA Risk Score 6
• The MESA Risk Score with CAC and the PCE plus CAC showed the best discrimination among patients with 5% to 20% estimated risk 6
• Coronary calcium scores can be used to identify individuals who would experience net benefit from primary prevention aspirin therapy, but only in those with lower bleeding risk and estimated ASCVD risk that is not low 3