Is functional coronary angiography (FCA) a cost-effective diagnostic tool for patients with suspected coronary artery disease (CAD)?

Cost-Effectiveness of Functional Coronary Angiography for Suspected CAD

Functional coronary angiography (FCA) is a cost-effective diagnostic tool for patients with suspected coronary artery disease (CAD), particularly when used selectively to assess intermediate coronary stenoses rather than routinely for all vessels.

Functional Coronary Angiography: Definition and Types

Functional coronary angiography refers to techniques that assess the hemodynamic significance of coronary stenoses during invasive coronary angiography (ICA), including:

• Fractional Flow Reserve (FFR) - significant when ≤0.8 1
• Instantaneous wave-Free Ratio (iFR) - significant when ≤0.89 1
• Quantitative Flow Ratio (QFR) - significant when ≤0.8 1

Evidence-Based Recommendations for FCA Use

The 2024 ESC guidelines strongly recommend:

1. Selective assessment of functional severity of intermediate diameter stenoses during ICA to guide revascularization decisions 1
2. Against systematic and routine wire-based coronary pressure assessment of all coronary vessels (Class III, Level A recommendation) 1

Cost-Effectiveness Analysis

The cost-effectiveness of FCA depends on:

Patient Selection

• Most cost-effective when used in patients with:
  • Intermediate coronary stenoses (40-90%)
  • Uncertain functional significance based on non-invasive testing
  • Moderate to high pre-test probability of CAD

Diagnostic Pathway Efficiency

• Sequential testing strategies incorporating functional assessment are more cost-effective than direct referral to invasive angiography 2
• A combined protocol integrating coronary anatomy and function is highly effective for accurate CAD diagnosis 3

Reduction in Unnecessary Procedures

• 20-25% of patients can avoid invasive testing using functional testing as a gateway to angiography, without substantial effects on outcomes 4
• FCA helps avoid unnecessary revascularization procedures for non-hemodynamically significant stenoses

Optimal Diagnostic Strategy for Suspected CAD

The most cost-effective approach follows this algorithm:

1. Initial non-invasive test based on pre-test likelihood of CAD:

   • Low to moderate (5-50%): CCTA as preferred initial test 1
   • Moderate to high (15-85%): Functional imaging (stress echo, SPECT, PET, or CMR) 1

2. Second-line testing:

   • If CCTA shows CAD of uncertain functional significance: Functional imaging 1
   • If functional imaging is inconclusive: Consider ICA with FCA 1

3. Invasive testing with FCA:

   • For patients with very high clinical likelihood (>85%) of CAD 1
   • For severe symptoms refractory to medical therapy 1
   • For angina at low exercise levels 1
   • When non-invasive tests are inconclusive 1

4. During ICA: Selectively assess intermediate stenoses with FFR/iFR/QFR 1

Pitfalls and Caveats

• Overuse of FCA: Systematic assessment of all vessels is not recommended and increases costs without clinical benefit 1
• Underuse of FCA: Relying solely on anatomical assessment may lead to unnecessary revascularization of non-functionally significant stenoses
• Technical considerations:
  • Radial artery access is recommended as the preferred access site for ICA 1
  • FFR requires adenosine administration which can cause transient AV block or bronchospasm
  • iFR doesn't require adenosine but may be less validated in certain lesion subsets

Conclusion from Evidence

The evidence strongly supports selective use of functional coronary angiography for intermediate stenoses. This approach optimizes patient outcomes by ensuring that only hemodynamically significant lesions are treated, while avoiding unnecessary procedures and their associated costs and risks.