From the Guidelines
A calcium score is a crucial medical test for assessing heart disease risk, and I strongly recommend it for individuals between 40-75 years old with intermediate cardiovascular risk factors, as it can help refine risk assessment and guide preventive interventions, such as statin therapy, as supported by the 2019 ACC/AHA guideline 1. The calcium score test is a specialized CT scan that measures the amount of calcium buildup in the coronary arteries, providing a direct visualization of actual plaque buildup.
- The test is non-invasive, takes about 10-15 minutes, and doesn't require contrast dye or special preparation.
- Scores range from 0 (no detectable calcium) to over 400 (extensive plaque buildup), with a score of 0 indicating low risk, 1-100 suggesting mild disease, 101-400 moderate disease, and above 400 extensive disease.
- A coronary artery calcium score of zero identifies individuals at lower risk of ASCVD events and death over a >10-year period, and may reclassify a patient downward into a lower risk group in which preventive interventions, such as statins, could be postponed, as noted in the MESA trial 1.
- The presence and severity of coronary artery calcium have been shown to be associated with the likelihood of benefit from statin therapy for ASCVD risk reduction, with a score ≥100 Agatston units (AU) or ≥75th age/sex/race percentile indicating a higher risk, as stated in the 2019 ACC/AHA guideline 1. Based on the calcium score, healthcare providers can recommend personalized heart disease prevention strategies, including lifestyle changes, medications, or further cardiac testing, ultimately improving morbidity, mortality, and quality of life outcomes.
- For example, a calcium score ≥100 may trigger the discussion for starting statin therapy, while a score of zero could be used as a rationale to emphasize lifestyle interventions and defer statin therapy, as suggested in the Mayo Clinic Proceedings study 1. Overall, the calcium score is a valuable tool for refining risk assessment and guiding preventive interventions, and its use is supported by recent guidelines and studies, including the 2019 ACC/AHA guideline 1 and the MESA trial 1.
From the Research
Significance of Calcium Score
The Coronary Artery Calcium (CAC) score is a significant marker of atherosclerotic plaque burden and an independent predictor of future myocardial infarction and mortality 2, 3. It provides incremental risk information beyond traditional risk calculators and is used for risk stratification in primary prevention of cardiovascular events.
Interpretation of CAC Score
The interpretation of CAC score is as follows:
- CAC=0: confers a very low risk of death, <1% at 10 years 3
- CAC=1-100: low risk, <10% 3
- CAC=101-400: intermediate risk, 10-20% 3
- CAC=101-400 & >75th centile: moderately high risk, 15-20% 3
- CAC >400: high risk, >20% 3
Management Recommendations
Management recommendations based on CAC score are:
- Optimal diet and lifestyle measures are encouraged in all risk groups 3
- Patients with moderately-high or high risk based on CAC score are recommended to receive preventative medical therapy such as aspirin and statins 2, 3
- Aspirin and statins are generally not recommended in patients with CAC <100 3
Cost-Effectiveness of CAC
The cost-effectiveness of CAC-based primary prevention recommendations is uncertain, with some studies suggesting that CAC testing can be cost-effective in intermediate risk patients, but only if statins are costly or significantly affect quality of life 4. There is currently no data in Australia and New Zealand that CAC is cost-effective in informing primary prevention decisions 3.
Role of CAC in Guiding Statin Therapy
CAC score can be used to guide statin therapy, with recent guidelines recommending CAC as an arbitrator of statin use 5, 6. CAC testing offers a model for initiating or prolonging preventative statin therapies and subsequently up- or down-risking of patients 6. However, it remains uncertain whether these recommendations have been universally followed 6.