What constitutes a functional assessment after a Coronary Computed Tomography Angiography (Coronary CTA) shows Coronary Artery Disease (Cardiac Roads) grade 3?

Functional Assessment After Coronary CTA Shows CAD-RADS 3

For patients with CAD-RADS 3 (moderate stenosis 50-69%) on Coronary CTA, functional assessment should include CT-FFR, CT myocardial perfusion imaging (CTP), or stress testing (exercise ECG, stress echocardiogram, SPECT, PET, or cardiac MRI) to determine the presence of ischemia and guide management decisions. 1

Understanding CAD-RADS 3 Classification

• CAD-RADS 3 represents moderate coronary stenosis (50-69%) which may or may not cause myocardial ischemia, necessitating functional assessment to determine hemodynamic significance 1
• This classification requires further evaluation beyond anatomical assessment to guide appropriate management and determine if revascularization is needed 1
• Functional assessment is critical as anatomical stenosis severity alone does not reliably predict hemodynamic significance 1

Recommended Functional Assessment Options

CT-Based Functional Assessment:

• CT-derived Fractional Flow Reserve (CT-FFR) - computational fluid dynamics applied to standard CCTA datasets to simulate pressure and flow across stenoses 1, 2
• CT Myocardial Perfusion Imaging (CTP) - evaluates myocardial blood flow under pharmacologic stress conditions 1, 2
• Results are classified as positive (I+), negative (I-), or borderline (I+/-) for ischemia 1

Non-CT Functional Assessment Options:

• Exercise Electrocardiogram Testing (ETT) - evaluates ECG changes during physical exertion 1
• Stress Echocardiography - assesses wall motion abnormalities during stress 1
• Single-Photon Emission Computed Tomography (SPECT) - nuclear imaging to evaluate myocardial perfusion 1
• Positron Emission Tomography (PET) - high-sensitivity nuclear imaging for perfusion defects 1
• Cardiac Magnetic Resonance Imaging (CMR) - evaluates perfusion and wall motion abnormalities 1
• Invasive FFR during catheterization - gold standard for lesion-specific ischemia assessment 1

Interpretation of Functional Assessment Results

• Positive functional assessment (I+) indicates hemodynamically significant stenosis requiring consideration of invasive coronary angiography (ICA), especially with persistent symptoms 1
• Negative functional assessment (I-) suggests medical therapy is appropriate without need for revascularization 1
• High-risk findings on functional assessment include:
  • Exercise ECG: Duke Treadmill Score < -10 1
  • SPECT/PET: ischemic area ≥10% of left ventricular myocardium 1
  • Stress echocardiography: ≥3 of 16 segments with stress-induced hypokinesia/akinesia 1
  • CMR: ≥2 of 16 segments with stress perfusion defects or ≥3 dobutamine-induced dysfunctional segments 1

Management Based on Functional Assessment Results

• If functional assessment is positive (I+):

  • Consider invasive coronary angiography (ICA), especially if symptoms persist despite optimal medical therapy 1
  • Evaluate for potential revascularization based on anatomical and functional findings 1

• If functional assessment is negative (I-):

  • Implement aggressive risk factor modification and preventive pharmacotherapy 1
  • Consider anti-anginal therapy per guideline-directed care 1
  • Continue clinical follow-up without invasive intervention 1

Clinical Considerations and Pitfalls

• Functional assessment should be considered when the information will change patient management decisions 1
• Patients with persistent symptoms despite adequate medical therapy should undergo functional assessment even with moderate stenosis 1
• Consider lesion location, plaque characteristics, and overall plaque burden when interpreting functional assessment results 1
• Avoid routine invasive angiography without functional assessment as it may lead to unnecessary procedures 3
• Sequential testing (anatomical followed by functional) may be necessary to establish accurate diagnosis and guide management 1

Special Situations

• In patients with inconclusive stress tests, coronary CTA with subsequent functional assessment provides incremental prognostic information 4
• The presence of high-risk plaque features may warrant more aggressive management even with borderline functional results 5
• For patients with acute chest pain and CAD-RADS 3, consider hospital admission with cardiology consultation and prompt functional assessment 1