Do we start with a coronary CTA (Computed Tomography Angiography) or send the patient for cardiac catheterization?

Coronary CTA Should Be the First-Line Test for Evaluating Suspected Coronary Artery Disease

Coronary CT Angiography (CCTA) should be used as the default first-line test for evaluating patients with suspected coronary artery disease, particularly those with low-to-intermediate pre-test probability of obstructive CAD, before proceeding to invasive cardiac catheterization. 1, 2

Evidence Supporting CCTA-First Approach

• CCTA has excellent diagnostic accuracy with a high negative predictive value (>95%), allowing confident exclusion of obstructive CAD in patients with suspected disease 2
• The European Society of Cardiology and American College of Cardiology recommend CCTA as the preferred initial test in patients with lower ranges of clinical likelihood of CAD, which represents the majority of patients with stable chest pain 1, 2
• A CCTA-first strategy does not result in more cardiac catheterizations and revascularization compared to functional testing approaches 1
• Data from UnitedHealthcare show that a CCTA-first strategy reduces costs for patients with stable chest pain compared to stress imaging 1

Patient Selection for CCTA vs. Cardiac Catheterization

• For patients with low to moderate (15-50%) pre-test likelihood of obstructive CAD, CCTA is recommended as the first-line test 2
• For patients with moderate to high (50-85%) pre-test likelihood, CCTA may still be considered when information about atherosclerosis is desired 2
• Direct invasive coronary angiography should be reserved for:
  • Patients with very high (>85%) pre-test likelihood of obstructive CAD 2
  • Patients with high clinical likelihood and severe symptoms refractory to medical therapy 1
  • Patients with typical angina at low level of exercise and clinical evaluation indicating high event risk 1

Benefits of CCTA Beyond Stenosis Detection

• CCTA provides valuable information about plaque composition and high-risk plaque features that have prognostic significance 2, 3
• Knowledge of plaque presence can help prevent or delay onset of cardiac events by encouraging patients to seek treatment and implement lifestyle changes 1
• CCTA can be complemented with CT-derived fractional flow reserve (CT-FFR) to assess the hemodynamic significance of intermediate stenoses without requiring invasive procedures 2, 4

Clinical Decision Algorithm

1. Assess pre-test likelihood of obstructive CAD based on clinical factors 2
2. For low to moderate pre-test likelihood (most patients):
   • Start with CCTA 1, 2
   • If CCTA shows no CAD or non-obstructive disease: medical management 5
   • If CCTA shows intermediate stenosis (50-69%): consider functional assessment with CT-FFR or stress testing 2
   • If CCTA shows severe stenosis (≥70%) or left main disease: proceed to invasive coronary angiography 2
3. For high pre-test likelihood or severe symptoms:
   • Consider direct invasive coronary angiography, especially when revascularization is likely needed 1

Limitations and Caveats

• CCTA is not recommended when extensive coronary calcification, irregular heart rate, significant obesity, or inability to cooperate with breath-hold commands make good image quality unlikely 1, 2
• In patients with previous revascularization (bypass grafts, stents), the accuracy of CCTA may be impaired by blooming artifacts 2
• CCTA has lower accuracy for in-stent restenosis evaluation for stents smaller than 3.0 mm in diameter 2
• Despite the evidence supporting CCTA-first approach, there are practical barriers in the US including reimbursement disparities and pre-authorization requirements that may limit implementation 1

By following this evidence-based approach, clinicians can optimize diagnostic pathways for patients with suspected CAD, potentially reducing unnecessary invasive procedures while improving patient outcomes.