From the Guidelines
A coronary artery calcium (CAC) score is a crucial tool for assessing cardiovascular risk, guiding preventive strategies, and making informed decisions about statin therapy, particularly for adults aged 40-75 with intermediate risk for heart disease but no symptoms. The test is performed using a specialized CT scan without contrast and measures the amount of calcium buildup in the coronary arteries, providing an assessment of cardiovascular risk 1. Scores range from zero (no detectable calcium) to over 400 (extensive calcification), with higher scores indicating greater risk of future cardiac events.
- A score of zero suggests very low risk,
- 1-100 indicates mild calcification,
- 101-400 moderate calcification, and
- above 400 extensive calcification. The test helps guide preventive strategies, including lifestyle modifications and medication decisions such as statins. For those with elevated scores, physicians may recommend aspirin (typically 81mg daily), moderate to high-intensity statins (like atorvastatin 20-80mg or rosuvastatin 10-40mg daily), and more aggressive management of risk factors like hypertension and diabetes 1. The CAC score is particularly useful because it detects actual atherosclerotic plaque rather than just risk factors, allowing for more personalized cardiovascular risk assessment and treatment planning 1. The radiation exposure is minimal (about 1 mSv) and the test typically costs between $100-400, though insurance coverage varies. According to the most recent guidelines, a CAC score of 0 can help downgrade risk and withhold statin therapy, while a CAC score >100 may initiate or consider statin therapy 1. Overall, the CAC score is a valuable tool for clinicians to refine risk assessment and guide treatment decisions, ultimately improving patient outcomes and reducing cardiovascular risk.
From the Research
Significance of Coronary Artery Calcium (CAC) Score
The CAC score is a useful tool in evaluating the risk of cardiovascular events in asymptomatic patients 2. A CAC score of zero determines excellent cardiovascular prognosis, with event rates lower than that of negative stress studies 2.
CAC Score and Cardiovascular Risk
Numerous prospective cohorts have validated CAC as an independent marker that improves prognostication in atherosclerotic cardiovascular disease (ASCVD) beyond traditional risk factors 3. The absence of CAC is associated with low risk of cardiovascular events compared with any CAC > 0 in both asymptomatic and symptomatic population without coronary artery disease 4.
CAC Score and Obstructive CAD
While many studies report CAC=0 to virtually exclude obstructive coronary artery disease (CAD), non-negligible rates of obstructive CAD despite CAC=0 are reported in certain populations 3. CAC=0 does not reliably exclude obstructive CAD in patients under 40 years, as they have a higher burden of non-calcified plaque 3.
CAC Score Categories
CAC scores can be categorized into zero (CAC = 0), minimal (CAC 1-10), and mild (CAC 11-100) 5. Individuals with minimal calcium scores (1-10) had greater noncalcified coronary plaque (NCAP) and total plaque volume than individuals with a calcium score of zero, placing them at higher coronary vascular disease (CVD) risk 5.
Prevalence of Noncalcified Plaques
In patients with a high clinical suspicion of CAD, the absence of coronary artery calcification does not rule out CAD; up to 6.4% of these patients have early CAD as evidenced by noncalcified plaques (NCP) detected by CCTA 6.
Key Points
- A CAC score of zero is associated with low risk of cardiovascular events
- CAC score is a useful tool in evaluating the risk of cardiovascular events in asymptomatic patients
- CAC=0 does not reliably exclude obstructive CAD in patients under 40 years
- Individuals with minimal calcium scores (1-10) are at higher CVD risk than those with a calcium score of zero
- The absence of coronary artery calcification does not rule out CAD in patients with a high clinical suspicion of CAD 2, 3, 5, 4, 6