How often should coronary computed tomography angiography (CTA) be repeated in patients with known coronary artery disease (CAD)?

Frequency of Coronary CTA Repetition in Patients with Known CAD

For patients with known coronary artery disease (CAD), coronary computed tomography angiography (CCTA) should be repeated every 3-5 years if the patient has nonobstructive CAD (<50% stenosis) and the results might change treatment decisions. 1

Recommendations Based on CAD Severity

Nonobstructive CAD (<50% stenosis)

• CCTA can be useful to determine progression of atherosclerotic plaque and development of obstructive CAD 1
• Repeat scanning intervals:
  • CAC score = 0: Every 5 years 1
  • CAC score 1-99: Every 3-5 years if results might change treatment decisions 1
  • CAC score ≥100 with LDL-C ≥70 mg/dL: Every 3 years to assess for accelerated progression (>20-25% per year) or increase to CAC score >300 1

Obstructive CAD (≥50% stenosis)

• For patients with obstructive CAD, stress imaging is generally preferred over repeat CCTA 1
• Stress testing options include:
  • Stress CMR (Cardiovascular Magnetic Resonance)
  • Stress echocardiography
  • Stress PET (Positron Emission Tomography)
  • Stress SPECT (Single-Photon Emission CT) 1

Special Considerations

High-Risk Patients

• For patients with high-risk CAD (left main stenosis ≥50% or anatomically significant 3-vessel disease with ≥70% stenosis) or frequent angina, invasive coronary angiography (ICA) is recommended rather than repeat CCTA 1

Stents

• CCTA has low accuracy for diagnosis of in-stent restenosis, particularly in stents smaller than 3.0 mm diameter 1
• For patients with coronary stents, stress imaging is generally preferred over CCTA 1

Prognostic Value of CCTA

The timing of repeat CCTA should consider the strong prognostic value of initial findings:

• Patients with normal coronary arteries on CCTA have excellent prognosis with annual event rates as low as 0.04% 2
• Patients with nonobstructive CAD have intermediate risk (annual event rate ~1.1%) 3
• Patients with obstructive CAD have higher risk (annual event rate ~1.5% or higher) 3, 2

Clinical Decision Algorithm

1. Assess patient's current CAD status:

   • Nonobstructive (<50% stenosis) vs. Obstructive (≥50% stenosis)
   • CAC score (if available)
   • Previous stents or bypass grafts

2. For nonobstructive CAD:

   • Repeat CCTA every 3-5 years if results might change management
   • Consider more frequent imaging (every 3 years) for patients with:
     • Diabetes
     • CAC scores ≥100
     • Multiple risk factors

3. For obstructive CAD:

   • Consider stress imaging rather than repeat CCTA
   • For high-risk CAD (left main or 3-vessel disease) or frequent symptoms, consider ICA instead

4. After change in symptoms:

   • New or worsening symptoms warrant reassessment regardless of time since last imaging
   • Optimize guideline-directed medical therapy before additional testing 1

Pitfalls to Avoid

• Don't rely on CCTA for in-stent restenosis evaluation in small stents (<3.0 mm)
• Extensive calcification can limit CCTA image quality; stress testing may be preferred in these cases
• Don't repeat CCTA too frequently (<3 years) in stable patients with nonobstructive disease
• Don't use CCTA when invasive coronary angiography is clearly indicated (high-risk anatomy with symptoms)

By following these evidence-based recommendations, clinicians can appropriately time repeat coronary CTA studies to monitor disease progression while avoiding unnecessary testing.