When should the SYNTAX (Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) score be calculated in patients with coronary artery disease?

When to Calculate the SYNTAX Score

The SYNTAX score should be calculated for all patients with complex coronary artery disease, particularly those with left main disease, three-vessel disease, or multivessel disease, to guide the decision between CABG and PCI. 1

Indications for SYNTAX Score Calculation

Mandatory Calculation:

• Unprotected Left Main Coronary Artery (ULCMA) Disease

  • Class IIa recommendation (Level of Evidence: B) 1
  • Essential for determining if PCI is a reasonable alternative to CABG
  • Critical when considering PCI for left main disease of any complexity

• Complex Three-Vessel Coronary Artery Disease

  • Particularly important when both CABG and PCI are technically feasible
  • Helps identify patients who would benefit more from CABG (SYNTAX score >22) 1

• Multivessel Disease with or without Diabetes

  • Guides optimal revascularization strategy
  • Particularly important in diabetic patients where CABG is generally preferred 1

Clinical Decision Points Based on SYNTAX Score:

1. Left Main Disease:

   • SYNTAX score ≤22 (low complexity): PCI is a reasonable alternative to CABG (Class I, LOE: A) 1
   • SYNTAX score 23-32 (intermediate complexity): PCI should be considered (Class IIa, LOE: A) 1
   • SYNTAX score ≥33 (high complexity): CABG is preferred (Class III: Harm for PCI) 1

2. Three-Vessel Disease:

   • SYNTAX score ≤22: Both PCI and CABG are reasonable options
   • SYNTAX score >22: CABG is preferred (Class IIa, LOE: B) 1

3. Diabetic Patients with Multivessel Disease:

   • CABG generally preferred regardless of SYNTAX score (Class I, LOE: A) 1
   • SYNTAX score still useful for risk stratification

When SYNTAX Score Can Be Ignored or Is Less Critical

• Single-vessel disease without left main involvement
• Two-vessel disease without proximal LAD involvement
• Acute STEMI with left main as culprit lesion and TIMI flow <3 (emergency setting)
• Patients who are not candidates for CABG due to prohibitive surgical risk
• Patients with clear indication for medical therapy only (no anatomic or physiologic criteria for revascularization)

Clinical Application and Interpretation

The SYNTAX score correlates with outcomes primarily in PCI patients, not in CABG patients 1. This is a critical point - a high SYNTAX score predicts worse outcomes with PCI but has minimal impact on CABG outcomes.

Long-term data shows that patients with high SYNTAX scores (≥33) have significantly higher rates of major adverse cardiac events (MACE) after PCI compared to those with lower scores 2, making CABG the preferred strategy for these patients.

Common Pitfalls to Avoid

• Underscoring: Investigators consistently underscore compared to core lab calculations by approximately 3.4 points 3. Consider this when calculating the score in clinical practice.
• Relying solely on anatomical SYNTAX score: Consider using SYNTAX Score II which incorporates clinical variables (age, creatinine clearance, LVEF, peripheral vascular disease, female sex, COPD) for more individualized decision-making 4.
• Ignoring calculation in complex disease: Failure to calculate the score in patients with complex coronary disease may lead to suboptimal revascularization strategy selection.
• Overreliance in simple disease: The score adds little value in simple, single-vessel disease.

The SYNTAX score has acceptable reproducibility (weighted kappa 0.45-0.59) 3 and should be calculated as part of a Heart Team approach for complex coronary artery disease to guide optimal revascularization strategy.