Management of Severe Coronary Artery Stenosis

Initial Assessment and Risk Stratification

• The American College of Radiology recommends that severe coronary stenosis (70-99%) on CT angiography is classified as CAD-RADS 4, which requires further evaluation and management 1, 2
• CAD-RADS 4 is further subdivided into CAD-RADS 4A: Severe stenosis (70-99%) in one or two vessels, and CAD-RADS 4B: Left main stenosis ≥50% or three-vessel obstructive disease (>70%) 2, 3

Management Algorithm Based on CAD-RADS Classification

• For CAD-RADS 4A, the American College of Cardiology recommends initiating aggressive risk factor modification and preventive pharmacotherapy, and implementing anti-anginal therapy per guideline-directed care 1, 3, 4
• For CAD-RADS 4A, functional assessment options include CT-derived fractional flow reserve (CT-FFR) 2, 5, CT myocardial perfusion imaging (CTP) 2, 3, and other stress testing (exercise ECG, stress echocardiogram, SPECT, PET, or cardiac MRI) 2, 6
• Invasive coronary angiography (ICA) is particularly favored if any of the following are present: very high-grade stenosis (>90%), high-risk plaque features, evidence of lesion-specific ischemia, or persistent symptoms despite optimal medical therapy 2, 3, 4

Revascularization Considerations

• The decision between percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) should be based on coronary anatomy complexity, left ventricular function, presence of comorbidities, and patient preference 1, 7, 8
• For single-vessel disease, PCI with stenting of the culprit lesion is typically the first choice 8
• For multivessel disease, CABG may offer survival benefit, especially with left ventricular dysfunction 7, 8

Functional Assessment During ICA

• When ICA is performed, selective assessment of functional severity of intermediate stenoses is recommended using fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR) (significant if ≤0.8 or ≤0.89, respectively), or quantitative flow ratio (QFR) (significant if ≤0.8) 5, 6

Special Considerations

• For patients with severe stenosis and acute chest pain, an immediate invasive strategy (<2 hours) may be warranted if there is hemodynamic instability, refractory angina, or other high-risk features 8, 9
• For stable patients with severe stenosis, a deferred approach (12-48 hours) while optimizing medical therapy may be reasonable 7, 10

Follow-up After Management

• After revascularization, patients require dual antiplatelet therapy (duration based on intervention type), continued risk factor modification, and regular clinical follow-up to assess for recurrent symptoms 1, 3, 6, 8