What do the latest guidelines recommend for revascularization of left‑main coronary artery disease, including criteria for PCI versus CABG, SYNTAX score thresholds, and antiplatelet therapy?

Latest Guidelines on Left Main Coronary Artery Disease Revascularization

CABG remains the gold standard for left main disease, but PCI is a reasonable alternative in anatomically favorable disease (SYNTAX score ≤22) with high surgical risk (STS >5%), or as equivalent therapy in low-complexity disease (SYNTAX ≤22) at low surgical risk. 1

Defining Significant Left Main Disease

• Left main stenosis ≥50% diameter is considered hemodynamically significant and warrants revascularization consideration 1, 2
• This threshold is lower than non-left main vessels (≥70%) due to the large myocardial territory at risk 2

CABG vs PCI: Decision Algorithm

Step 1: Assess Surgical Risk (STS Score)

Calculate the Society of Thoracic Surgeons (STS) predicted operative mortality score 1:

• Low surgical risk (STS <2%): CABG is preferred 1
• Intermediate surgical risk (STS 2-5%): Either modality reasonable based on anatomy 1
• High surgical risk (STS >5%): PCI becomes more favorable if anatomy permits 1

Step 2: Assess Anatomic Complexity (SYNTAX Score)

Calculate the SYNTAX score to quantify coronary complexity 1:

• Low complexity (SYNTAX ≤22): PCI is equivalent to CABG for survival 1
• **Low-intermediate complexity (SYNTAX <33)**: PCI reasonable if surgical risk elevated (STS >2%) 1
• High complexity (SYNTAX >22): CABG strongly preferred 1

Step 3: Apply Clinical Context

Class I Indications for CABG (must perform):

• Any left main stenosis ≥50% in low surgical risk patients 1
• Left main disease with multivessel involvement and diabetes 1
• Left main disease with LVEF ≤35% 1

Class IIa Indications for PCI (reasonable alternative):

• SYNTAX ≤22 (ostial or trunk left main) AND STS >5% 1
• SYNTAX ≤22 at low surgical risk (equivalent to CABG) 1
• UA/NSTEMI with left main culprit when not a CABG candidate 1
• STEMI with left main culprit when PCI faster/safer than CABG 1

Class IIb Indications for PCI (may be reasonable):

• SYNTAX <33 (bifurcation left main) AND STS >2% with comorbidities (severe COPD, prior stroke, prior cardiac surgery) 1

Class III Harm (do not perform PCI):

• Unfavorable anatomy for PCI (high SYNTAX score) in good surgical candidates 1

Special Populations

Diabetes Mellitus

• CABG is strongly preferred over PCI regardless of SYNTAX score in diabetic patients with left main plus multivessel disease 1, 3
• CABG with LIMA to LAD provides superior long-term outcomes 1, 3

Left Ventricular Dysfunction

• LVEF ≤35%: CABG recommended over medical therapy alone to improve survival 1
• LVEF 35-50%: CABG reasonable when viable myocardium present 1
• Heart Team evaluation mandatory to assess viability, comorbidities, and life expectancy 1

Acute Coronary Syndromes

• STEMI with left main culprit: PCI reasonable when distal TIMI flow <3 and PCI can be performed faster than CABG 1
• UA/NSTEMI with left main culprit: PCI reasonable if patient not a CABG candidate 1

PCI Technical Considerations When Selected

Mandatory Adjuncts

• Intracoronary imaging (IVUS or OCT) is required for left main PCI to optimize stent deployment 1
• Pressure wire assessment (FFR or iFR) recommended for multivessel disease to guide complete revascularization 1

Bifurcation Technique

• For distal left main bifurcation lesions, provisional single-stent strategy preferred unless true bifurcation with significant side branch disease 4
• Double-kiss crush technique may reduce target vessel revascularization in complex bifurcations 4

Antiplatelet Therapy

After PCI:

• Dual antiplatelet therapy (aspirin + P2Y12 inhibitor) required for minimum 1 month after bare-metal stent, 6-12 months after drug-eluting stent 5
• Extended DAPT beyond 12 months may be considered in high ischemic/low bleeding risk patients 5

After CABG:

• Aspirin should be started within 6 hours post-operatively and continued indefinitely 1
• P2Y12 inhibitor not routinely indicated unless recent ACS or PCI 1

Heart Team Approach

• Multidisciplinary Heart Team discussion is mandatory for all left main disease cases 1
• Team must include interventional cardiologist, cardiac surgeon, and general cardiologist at minimum 1
• Discussion should incorporate SYNTAX score, STS score, patient preferences, and completeness of revascularization achievable 1, 4

Critical Pitfalls to Avoid

• Do not use PCI for high SYNTAX score (>22) left main disease in good surgical candidates - this is Class III Harm with significantly worse outcomes 1
• Do not forget the diabetes exception - CABG is superior regardless of anatomy in diabetic patients with multivessel disease 1, 3
• Do not perform left main PCI without intracoronary imaging - IVUS/OCT guidance is Class I recommendation to ensure adequate stent expansion 1
• Do not ignore the 50% threshold - left main requires intervention at 50% stenosis, not the 70% threshold used for other vessels 2
• Do not delay revascularization in STEMI - when left main is the culprit, PCI is reasonable if it can be performed faster than CABG 1

Long-Term Outcomes Data

Recent real-world data through 14 years of follow-up demonstrates CABG superiority over PCI for left main disease: mortality 40.0% vs 58.4% (HR 0.58), MI 10.7% vs 22.3% (HR 0.40), and repeat revascularization 5.4% vs 16.3% (HR 0.25) 6. These findings reinforce CABG as the preferred strategy in acceptable surgical candidates despite improvements in PCI techniques 6.