What are the implications of left dominant coronary circulation on surgical aortic valve replacement?

Implications of Left Dominant Coronary Circulation on Surgical Aortic Valve Replacement

In patients with left dominant coronary circulation, surgical aortic valve replacement requires special consideration due to increased risk of myocardial ischemia and mortality, as the left coronary system supplies a larger portion of the myocardium. While guidelines don't specifically address left dominance, evidence-based principles can guide management.

Preoperative Considerations

Coronary Anatomy Assessment

• Complete coronary angiography is mandatory to identify left dominance pattern 1
• CT coronary angiography may be used in patients with low pretest probability for CAD 1
• Careful assessment of the left coronary system is critical as it supplies both the left and right ventricle in left dominant circulation

Risk Stratification

• Left dominance increases vulnerability to myocardial ischemia during aortic valve surgery
• Higher risk of perioperative complications when SAVR is combined with CABG (mortality 3% vs. standard risk) 1
• Consider STS risk score calculation with attention to coronary anatomy pattern

Intraoperative Management

Myocardial Protection Strategies

• Modified cardioplegia delivery is essential:
  • Ensure adequate distribution to the entire myocardium
  • Consider retrograde cardioplegia to supplement antegrade delivery
  • More frequent cardioplegia doses may be necessary
  • Maintain mild-to-moderate hypothermia (29-30°C) 2

Concomitant Coronary Revascularization

• CABG should be combined with SAVR when significant CAD is present 1
• For left main or proximal CAD in left dominant circulation:
  • CABG is strongly indicated (Class I recommendation) 1
  • Complete revascularization is particularly important
• For complex bifurcation left main and/or multivessel CAD with SYNTAX score >33:
  • SAVR and CABG are preferred over TAVI and PCI 1

Technical Considerations

• Careful handling of the left coronary ostium during valve implantation
• Ensure proper valve sizing to avoid left coronary ostial obstruction
• Consider supra-annular valve positioning to maintain coronary flow

Postoperative Management

Hemodynamic Monitoring

• More aggressive monitoring for signs of myocardial ischemia
• Lower threshold for post-operative coronary angiography if ischemia is suspected
• Careful management of heart rate and blood pressure to optimize coronary perfusion

Antiplatelet/Anticoagulation Management

• Standard anticoagulation protocols based on valve type
• For mechanical valves: warfarin with target INR based on valve position and patient risk factors 3
• For bioprosthetic valves: consider extended antiplatelet therapy in left dominant patients

Special Considerations

Alternative Approaches

• In high-risk patients, consider:
  • Minimally invasive approaches if expertise is available 4
  • TAVR may be reasonable for patients at high surgical risk 1
  • "Open IMA technique" with minimal dissection for redo cases 2

Potential Complications

• Higher risk of:
  • Myocardial infarction due to greater myocardium at risk
  • Arrhythmias, particularly if ischemia occurs
  • Heart failure if significant myocardial injury occurs

Follow-up Recommendations

• Earlier and more frequent post-discharge follow-up
• Lower threshold for cardiac imaging if symptoms develop
• Aggressive management of cardiovascular risk factors

Left dominant coronary circulation represents an important anatomical variant that requires special attention during surgical aortic valve replacement. The comprehensive approach outlined above can help mitigate the increased risks associated with this coronary pattern.