Coronary Dominance: Right, Left, and Co-Dominant Patterns

Coronary dominance describes which artery gives rise to the posterior descending artery. Understanding dominance is critical for coronary angiography, cardiac surgery, and predicting infarct territories.

Coronary Circulation 4 min read
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Coronary dominance refers to which coronary artery supplies the posterior descending artery (PDA) and, consequently, the inferior wall of the left ventricle and the posterior interventricular septum.

Definition of Dominance

Coronary dominance is defined by the origin of the posterior descending artery (PDA):

Dominant artery: The artery that reaches the crux of the heart and gives rise to the PDA and atrioventricular nodal artery

Crux of the heart: The intersection of the posterior atrioventricular groove and the posterior interventricular groove

Types of Coronary Dominance

Right Dominance

The right coronary artery (RCA) gives off the PDA and posterolateral branches. The RCA reaches the crux and terminates as the PDA.

Frequency: 70-80% of the population

Characteristics:

  • RCA supplies the inferior wall, posterior septum, and AV node
  • LCx is smaller and terminates as obtuse marginal branches
  • RCA provides the AV nodal artery

Left Dominance

The left circumflex artery (LCx) gives off the PDA and posterolateral branches. The LCx reaches the crux and terminates as the PDA.

Frequency: 10-15% of the population

Characteristics:

  • LCx supplies the inferior wall, posterior septum, and AV node
  • RCA is small and supplies primarily the right ventricle
  • LCx provides the AV nodal artery

Co-Dominance (Balanced Circulation)

Both the RCA and LCx reach the crux and contribute to the PDA and posterolateral supply. The PDA may have a dual origin.

Frequency: 10-15% of the population

Characteristics:

  • RCA provides posterolateral branches to the right ventricle
  • LCx provides posterolateral branches to the left ventricle
  • AV nodal artery may arise from either artery

Comparison of Dominance Patterns

Feature Right-Dominant Left-Dominant Co-Dominant
Frequency 70-80% 10-15% 10-15%
PDA origin RCA LCx Both
AV nodal artery RCA (80-90%) LCx (90%) Variable
Inferior LV supply RCA LCx Both
Posterior septum RCA LCx Both
RCA size Large Small Medium
LCx size Small Large Medium

Anatomic Basis

Right-Dominant Heart

The RCA continues beyond the acute margin, courses along the posterior atrioventricular groove to the crux, and gives off:

  1. AV nodal artery (at the crux)
  2. Posterior descending artery (PDA)
  3. Posterolateral branches (to the posterior LV)

Left-Dominant Heart

The LCx continues along the posterior atrioventricular groove beyond the obtuse margin, reaches the crux, and gives off:

  1. AV nodal artery
  2. Posterior descending artery (PDA)
  3. Posterolateral branches (to the posterior LV)

Co-Dominant Heart

Both the RCA and LCx supply the posterior structures:

  • RCA supplies the right-sided posterior septum and right ventricle
  • LCx supplies the left-sided posterior septum and left ventricle

Clinical Significance

Myocardial Infarction Patterns

Right-Dominant Heart:

  • RCA occlusion causes inferior MI with posterior septal involvement
  • Proximal RCA occlusion causes RV infarction
  • SA nodal ischemia (60%)
  • AV nodal ischemia (80-90%)

Left-Dominant Heart:

  • LCx occlusion causes inferior and posterior MI
  • No RV involvement with LCx occlusion
  • AV nodal ischemia (if LCx supplies AV node)
  • Larger territory at risk with proximal LCx occlusion

Co-Dominant Heart:

  • More favorable outcomes with single-vessel occlusion
  • Smaller infarct territories
  • Lower risk of AV block

Implications for Coronary Angiography

Dominance Catheter Selection Injection Priority
Right-dominant Standard Judkins RCA (supplies inferior wall)
Left-dominant Larger LCx may need larger catheters LCx (supplies inferior wall)
Co-dominant Standard approach Both arteries equally

Implications for Cardiac Surgery

Coronary bypass graft planning:

  • Right-dominant: RCA targets important for inferior wall revascularization
  • Left-dominant: LCx targets important for inferior wall revascularization
  • Grafting smaller vessels may have lower patency

Valve surgery:

  • Left-dominant: LCX at higher risk during mitral valve surgery
  • Right-dominant: RCA at higher risk during tricuspid valve surgery

Implications for Transcatheter Valve Therapy

TAVR (Transcatheter Aortic Valve Replacement):

  • Coronary occlusion risk depends on sinus height and leaflet anatomy
  • Dominance affects which coronary is more critical to protect

Mitral valve interventions:

  • The LCx courses near the mitral annulus
  • Left-dominant patients have a larger LCx at risk during annular procedures

Prognostic Significance

Left dominance has been associated with:

  • Potentially larger infarct size with LCx occlusion
  • Higher risk of complete heart block with LCx occlusion
  • No significant difference in long-term survival in most studies

Anatomic Reporting

When describing coronary anatomy, the standard format includes:

  1. Dominance pattern
  2. Anomalies (separate ostia, anomalous origin)
  3. Significant stenoses (location, severity, vessel)
  4. Myocardial bridges
  5. Collateral circulation