Is the calcium deposit test valuable in assessing cardiovascular risk?

Coronary Artery Calcium Testing for Cardiovascular Risk Assessment

Yes, the coronary artery calcium (CAC) test is valuable in assessing cardiovascular risk, particularly for individuals at borderline or intermediate risk where traditional risk assessment is uncertain. 1

Clinical Utility of CAC Testing

Appropriate Patient Selection

• Recommended for:

  • Individuals with intermediate predicted risk (≥7.5% to <20%) by the Pooled Cohort Equations 1
  • Select adults with borderline risk (5% to <7.5%) 1
  • Patients where risk assessment is uncertain after considering traditional risk factors 1

• Not recommended for:

  • Low-risk individuals (<6% 10-year risk) 1
  • Men under 40 years and women under 50 years due to low prevalence of detectable calcium 1

Risk Reclassification Power

• CAC scoring provides superior discrimination and risk reclassification compared to other subclinical imaging markers or biomarkers 1
• Can effectively reclassify risk in both directions:
  • Upward reclassification if CAC score ≥100 Agatston units (AU) or ≥75th age/sex/race percentile 1
  • Downward reclassification if CAC score is zero 1

Interpreting CAC Scores

Risk Categories

• CAC = 0: Excellent prognosis, annual mortality rate <0.5%, coronary event rate 0.4% over 3-5 years 2
• CAC 1-99: Mild to moderate risk, 1.2-2.2 times higher risk of cardiovascular events 2
• CAC 100-399: Moderate to high risk, 4.3 times higher relative risk 2
• CAC ≥400: Severe to very high risk, 7.2 times higher relative risk 2
• CAC ≥1000: Extremely high risk, 10.8 times higher relative risk 2

Clinical Impact

• A CAC score of zero identifies individuals at lower risk of ASCVD events and death over >10 years 1
• Patients with CAC=0 appear to derive little or no benefit from statins for ASCVD risk reduction 1
• High CAC scores strongly associate with 10-year ASCVD risk across age, sex, and racial/ethnic groups 1

Practical Implementation

Testing Procedure

• Uses either multidetector row CT or electron beam tomography 1
• Performed with prospective ECG triggering (preferred method) 1
• Low radiation dose (typical effective dose of 0.9-1.1 mSv) 1
• Comparable to radiation from 1-2 mammograms 1

Follow-up Recommendations

Based on CAC score 2:

• CAC = 0: Repeat in 5-7 years
• CAC 1-99: Repeat in 3-5 years
• CAC ≥100 or diabetes: Repeat in 3 years

Limitations and Considerations

• The incremental gain in C-statistic from adding CAC to traditional risk scores is modest (0.036) 3
• High rates of reclassification can occur, but most reclassified patients still don't experience events during follow-up 3
• CAC scoring cannot detect non-calcified plaque 1
• Absence of CAC does not completely rule out coronary artery disease 1
• Cost, incidental findings, and radiation exposure must be considered against potential benefits 3

Clinical Application Algorithm

1. First step: Calculate 10-year ASCVD risk using Pooled Cohort Equations
2. If risk is borderline (5% to <7.5%) or intermediate (≥7.5% to <20%):
   • Consider CAC testing for further risk stratification
3. Based on CAC results:
   • CAC = 0: Consider de-escalation of preventive therapy (may defer statin)
   • CAC 1-99: Consider moderate-intensity statin therapy
   • CAC ≥100: Consider high-intensity statin therapy
   • CAC ≥400: Consider high-intensity statin plus additional preventive measures

CAC testing provides valuable information for cardiovascular risk assessment, particularly when traditional risk assessment leaves uncertainty about appropriate preventive interventions.