What are the management guidelines for coronary artery stenosis based on percent blockage?

Guidelines for Coronary Artery Stenosis Management Based on Percent Blockage

Coronary artery stenosis management should be guided by the degree of stenosis, with specific thresholds determining the need for intervention: ≥50% for left main stenosis, ≥70% for other major coronary vessels, or 30-70% stenosis with FFR ≤0.8 indicating functional significance.

Classification of Coronary Artery Stenosis by Percent Blockage

The Coronary Artery Disease - Reporting and Data System (CAD-RADS) provides standardized categories for coronary stenosis 1:

• CAD-RADS 0: 0% stenosis (normal)
• CAD-RADS 1: 1-24% stenosis (minimal)
• CAD-RADS 2: 25-49% stenosis (mild)
• CAD-RADS 3: 50-69% stenosis (moderate)
• CAD-RADS 4A: 70-99% stenosis (severe)
• CAD-RADS 4B: Left main stenosis >50% or 3-vessel disease with ≥70% stenosis
• CAD-RADS 5: 100% stenosis (total occlusion)

Diagnostic Evaluation

Initial Assessment

• For patients with low to moderate (>5%-50%) pre-test likelihood of obstructive CAD, CCTA is recommended as the preferred initial diagnostic test 1
• For intermediate stenosis, functional assessment is essential using:
  • FFR/iFR (significant if ≤0.8 or ≤0.89, respectively)
  • QFR (significant if ≤0.8) 1

Defining Significant Stenosis

Significant coronary artery disease is defined as:

• 50% stenosis of the left main stem

• 70% stenosis in a major coronary vessel

• 30-70% stenosis with FFR ≤0.8 2

Management Based on Percent Stenosis

Non-obstructive Disease (CAD-RADS 0-2: 0-49% stenosis)

• Optimal medical therapy including:
  • High-intensity statin therapy (LDL-C goal <1.4 mmol/L or 55 mg/dL) 1
  • Antianginal medications (beta-blockers and/or calcium channel blockers) 1
  • Risk factor modification
  • Regular follow-up

Moderate Stenosis (CAD-RADS 3: 50-69% stenosis)

• Functional testing is recommended to determine hemodynamic significance
• If functionally significant:
  • Consider revascularization for symptom improvement 1
  • Optimize medical therapy
• If not functionally significant:
  • Continue optimal medical therapy
  • Regular follow-up

Severe Stenosis (CAD-RADS 4A: 70-99% stenosis)

• Revascularization is recommended in addition to medical therapy for:
  • Functionally significant single- or two-vessel disease involving the proximal LAD 1
  • Patients with persistent angina despite medical therapy 1

High-Risk Anatomy (CAD-RADS 4B)

• Left main stenosis ≥50%:

  • CABG is recommended over medical therapy alone to improve survival 1
  • CABG is generally preferred over PCI due to lower risk of spontaneous MI and repeat revascularization 1
  • PCI may be considered for left main stenosis with low anatomical complexity (SYNTAX score ≤22) 1

• Three-vessel disease with ≥70% stenosis:

  • Revascularization is recommended to improve long-term survival and reduce cardiovascular mortality 1
  • CABG is generally preferred for complex disease (high SYNTAX score)

Total Occlusion (CAD-RADS 5: 100% stenosis)

• Evaluate for viability of the myocardium in the territory supplied
• If viable myocardium is present and symptoms persist despite medical therapy:
  • Consider revascularization (PCI or CABG)
• Chronic total occlusions often lead to selection of CABG over PCI 3

Special Considerations

Reduced Left Ventricular Function

• In patients with LVEF ≤35% and multivessel CAD:
  • CABG is recommended over medical therapy alone to improve long-term survival 1
  • Careful evaluation by a Heart Team is recommended 1

Asymptomatic Patients with High-Risk Findings

Invasive coronary angiography with possible revascularization is recommended for asymptomatic patients with high-risk findings:

• Left main disease with ≥50% stenosis
• Three-vessel disease with ≥70% stenosis
• Two-vessel disease with ≥70% stenosis including the proximal LAD 1

Decision-Making Process

• A Heart Team approach is recommended for complex cases, particularly when CABG and PCI hold the same level of recommendation 1
• Patient preferences, comorbidities, and quality of life should be considered in the decision-making process 1
• The SYNTAX score should be calculated to assess anatomical complexity and guide the choice between CABG and PCI 1

Pitfalls and Caveats

• Visual assessment of stenosis severity correlates poorly with functional significance - approximately 35% of angiographically moderate (50-70%) stenoses are functionally significant, while 20% of severe (71-90%) stenoses are not 1
• Lesions in larger arteries (left main, proximal LAD) are more likely to be functionally significant at lower percent stenosis compared to smaller vessels 1
• The threshold for functional assessment should be lower (≥40% diameter stenosis) for larger arteries 1
• Patients with significant RCA stenosis (≥70%) undergoing intervention on the left coronary system have increased risk of complications 4