Stenosis Thresholds for Percutaneous Coronary Intervention (PCI)
PCI is indicated for coronary artery stenosis of >50% diameter in the left main coronary artery and >70% diameter in non-left main coronary arteries when accompanied by symptoms or evidence of ischemia. 1
Anatomic Criteria for PCI
The decision to perform PCI is based on specific anatomic thresholds that vary by coronary artery location:
- Left main coronary artery: >50% diameter stenosis 1
- Non-left main coronary arteries: >70% diameter stenosis 1
Clinical Context for PCI Decision-Making
Stenosis severity alone is insufficient for determining the need for PCI. The following factors must be considered:
Required Clinical Factors
- Symptoms: Unacceptable angina despite guideline-directed medical therapy (GDMT) 1
- Objective evidence of ischemia: Particularly important for intermediate stenoses 2
- Viability of myocardium: PCI should target viable ischemic myocardium 1
Contraindications
PCI should not be performed when:
- Stenosis is <50% in left main or <70% in non-left main arteries without physiological evidence of ischemia 1
- Patient cannot tolerate or comply with dual antiplatelet therapy 1
Special Clinical Scenarios
Left Main Disease
- >50% stenosis: Class I indication for CABG 1
- >50% stenosis with low SYNTAX score (<22): PCI may be reasonable as alternative to CABG 1
- >50% stenosis with unfavorable anatomy: PCI should not be performed (Class III: Harm) 1
Multivessel Disease
- >70% stenosis in 3 major vessels or proximal LAD plus another major vessel: CABG preferred 1
- >70% stenosis with diabetes: CABG generally preferred over PCI 1
- Complex 3-vessel disease (SYNTAX score >22): CABG preferred over PCI 1
Acute Coronary Syndromes
- >50% stenosis in unprotected left main as culprit in UA/NSTEMI: PCI reasonable if not a CABG candidate 1
- >50% stenosis in unprotected left main as culprit in STEMI with TIMI flow <3: PCI reasonable if can be performed more rapidly than CABG 1
Physiological Assessment
When anatomic criteria are borderline or unclear, functional assessment is crucial:
- Fractional Flow Reserve (FFR) <0.75 indicates functionally significant stenosis requiring intervention 3
- Deferring PCI for lesions with FFR ≥0.75 is associated with excellent 5-year outcomes 3
Common Pitfalls to Avoid
Performing PCI based on anatomy alone: The DEFER study showed that PCI of functionally non-significant stenoses (FFR ≥0.75) provides no benefit over medical therapy 3
Neglecting post-PCI antiplatelet therapy: Premature discontinuation of dual antiplatelet therapy can lead to catastrophic stent thrombosis, especially with drug-eluting stents 4
Underestimating bifurcation lesions: Simple stenting approaches for bifurcation lesions with ≥70% stenosis in major side branches can lead to significant periprocedural myocardial infarction 5
Performing PCI in severe aortic stenosis: PCI alone in patients with severe aortic stenosis and coexisting CAD is associated with poor outcomes 6
By adhering to these evidence-based thresholds and considering both anatomic and physiological criteria, clinicians can optimize outcomes for patients requiring coronary revascularization.