How often should a cardiac calcium score be done?

Frequency of Coronary Artery Calcium (CAC) Scoring

For patients with a CAC score of 0, repeat testing should be done in 5-7 years; for scores of 1-99, repeat in 3-5 years; and for scores ≥100, repeat in 3 years. 1

CAC Score-Based Testing Intervals

The recommended frequency for repeat CAC scoring depends on the initial score:

• CAC score of 0 (very low risk):

  • Repeat in 5-7 years 1
  • Not sooner than 5 years 2

• CAC score of 1-99 (low to intermediate risk):

  • Repeat in 3-5 years 1

• CAC score ≥100 or patients with diabetes:

  • Repeat in approximately 3 years 1

Risk Stratification by CAC Score

CAC scoring provides valuable risk stratification information:

• CAC = 0: Very low risk, annual mortality rate <0.5%, 10-year risk <1% 1, 2
• CAC = 1-99: Low/intermediate risk, 1.2-2.2× increased risk of cardiovascular events 1, 2
• CAC = 100-399: Moderate/high risk, 1.5-3.8× increased risk 1, 2
• CAC ≥400: Severe/very high risk, 2.1-5.9× increased risk 1, 2

Clinical Application Guidelines

The American College of Cardiology/American Heart Association guidelines recommend CAC scoring for:

• Intermediate-risk asymptomatic patients (7.5%-20% 10-year ASCVD risk) 3, 1
• Patients at borderline risk (5%-7.5%) with risk-enhancing factors 3
• Decision-making regarding statin therapy initiation 3

Candidates who may benefit from CAC scoring:

• Patients reluctant to initiate statin therapy 3
• Patients concerned about restarting statins after discontinuation due to side effects 3
• Older adults (men 55-80, women 60-80) with low risk factor burden 3
• Middle-aged adults (40-55) with borderline risk (5%-7.5%) plus risk-enhancing factors 3

Important Considerations

• Radiation exposure: While minimal, radiation exposure should be considered when planning repeat scans 1
• Limitations: CAC scoring has reduced accuracy in patients with certain metabolic conditions (diabetes, uremia) and disorders affecting calcium-phosphate homeostasis 1
• Statin effect: Prolonged statin therapy may increase CAC scores due to plaque stabilization, which should be considered when interpreting serial scans 1
• Cost-effectiveness: Currently, there is limited data on cost-effectiveness in Australia and New Zealand 2, though in the US it's considered reasonable for intermediate-risk patients

Clinical Pitfalls to Avoid

• Don't repeat too frequently: Repeating CAC scoring more often than recommended provides little additional information and increases radiation exposure
• Don't ignore risk factors in CAC=0 patients: A zero score doesn't eliminate risk in patients who smoke, have diabetes, or have a family history of premature ASCVD 3
• Don't use for low-risk patients: The American College of Cardiology recommends against CAC scoring for low-risk patients (Class III recommendation) 1
• Don't use as standalone test: CAC scoring should be integrated with traditional risk factor assessment for optimal risk stratification 4

By following these evidence-based intervals for CAC scoring, clinicians can appropriately monitor atherosclerotic burden while minimizing unnecessary testing and radiation exposure.