At what percentage of coronary artery blockage is stenting typically warranted?

Coronary Artery Stenting Thresholds

Stenting is warranted for coronary stenoses ≥70% diameter in non-left main vessels when patients have unacceptable angina despite guideline-directed medical therapy, or for stenoses ≥50% in the left main coronary artery. 1

Anatomic Thresholds for Revascularization

Left Main Disease

• ≥50% diameter stenosis of the left main coronary artery meets anatomic criteria for revascularization 1
• CABG is the Class I recommendation for improving survival in left main disease ≥50% 1
• PCI may be reasonable (Class IIa) as an alternative to CABG in selected stable patients with low-intermediate SYNTAX scores (<33) and clinical characteristics predicting increased surgical risk 1

Non-Left Main Vessels

• ≥70% diameter stenosis in major coronary arteries is the threshold for revascularization to improve symptoms or survival 1
• This applies to single-vessel disease, multivessel disease, and proximal LAD stenosis 1
• Stenoses of 50-70% are considered "moderate" and may warrant revascularization in specific contexts (see below) 1

Physiologic Assessment Overrides Pure Anatomy

The critical caveat is that anatomic stenosis severity alone is insufficient—physiologic significance must be demonstrated. 1

Fractional Flow Reserve (FFR) Criteria

• FFR ≤0.80 indicates hemodynamically significant stenosis warranting intervention 2
• FFR >0.80 suggests deferral of PCI is safe, even with angiographically intermediate lesions 2
• FFR ≤0.75 has 100% specificity for inducible ischemia 2
• The "gray zone" of 0.75-0.80 requires clinical judgment 2

When to Use FFR

• FFR is recommended (Class IIa, Level A) for intermediate stenoses (30-70% luminal narrowing) in patients with anginal symptoms 2
• FFR-guided PCI results in significantly lower event rates compared to angiography-guided PCI (13.2% vs 18.3% at 1 year, P=0.02) 2
• FFR assessment results in fewer stents placed without adverse outcomes 2

Clinical Context Modifies Thresholds

For Symptom Relief (Class I)

• Stenosis ≥70% with unacceptable angina despite guideline-directed medical therapy warrants CABG or PCI 1
• This is the most common indication in clinical practice 1

For Survival Benefit

• Three-vessel disease with ≥70% stenosis (with or without proximal LAD involvement): CABG preferred over PCI 1
• Proximal LAD stenosis ≥70% plus one other major vessel: CABG improves survival 1
• Two-vessel disease with ≥70% stenosis and extensive ischemia (>20% perfusion defect): CABG reasonable 1
• Diabetes with multivessel disease ≥70%: CABG strongly preferred over PCI 1

Evidence of Ischemia Required

• High-risk stress test criteria 1

• 20% perfusion defect on myocardial perfusion imaging 1

• Abnormal intracoronary hemodynamic evaluation (FFR) 1, 2
• Target vessels supplying large areas of viable myocardium 1

Critical Exclusion Criteria (Class III: Harm)

Revascularization should NOT be performed if anatomic criteria (<50% left main or <70% non-left main) OR physiologic criteria (normal FFR) are not met. 1

This is a Class III: Harm recommendation, meaning intervention in the absence of these thresholds causes more harm than benefit 1

Special Populations

Moderate Stenoses (50-70%)

• May warrant intervention during valve surgery (AVR with CABG) 1
• Require physiologic assessment (FFR) or documented ischemia in other contexts 2
• Left internal mammary artery grafting reasonable for LAD stenoses 50-70% during AVR 1

Acute Coronary Syndromes

• Different thresholds apply—culprit lesions warrant intervention regardless of percentage if causing acute ischemia 1
• Survivors of sudden cardiac death with ≥70% stenosis in major vessel: revascularization improves survival 1

Common Pitfalls to Avoid

• Visual angiographic assessment overestimates stenosis severity when lesions are ≥50%, leading to unnecessary interventions 1
• Diffuse disease without normal reference segments causes underestimation of severity 1
• Intermediate lesions (40-70%) require FFR assessment—many angiographically "severe" lesions are not hemodynamically significant 1, 2
• Stenting without ability to tolerate dual antiplatelet therapy is Class III: Harm 1