Coronary Dominance

Definition

Coronary dominance refers to which coronary artery gives rise to the posterior interventricular artery (posterior descending artery) and supplies the atrioventricular (AV) node.

The dominant artery is the one that reaches the crux of the heart (the point where the posterior interventricular sulcus meets the atrioventricular sulcus) and gives off the posterior interventricular branch.

Types

Type	Posterior Interventricular Artery	Frequency
Right dominant	Branch of the right coronary artery	~90%
Left dominant	Branch of the circumflex artery (LCA)	~10%
Codominant / Balanced	Contributions from both RCA and circumflex	Minority

Right Dominant Heart (90%)

• The RCA crosses the crux and gives off the posterior interventricular artery.
• The RCA also supplies the AV node (via the AV nodal artery, which arises at the crux).
• The circumflex artery terminates before or at the posterior interventricular groove.

Left Dominant Heart (10%)

• The circumflex artery (branch of the LCA) crosses the crux.
• The circumflex artery gives off both the posterior interventricular artery and the AV nodal artery.
• In left dominant hearts, the RCA is relatively small and does not reach the crux.
• In left dominant hearts, the LCA supplies the AV node — meaning LCA occlusion can cause AV block.

Clinical Importance

• In right dominant hearts, RCA occlusion is more likely to cause:

  • Inferior wall MI (posterior interventricular territory)
  • AV block (AV nodal artery occlusion)
  • SA node dysfunction (SA nodal artery from RCA in 60%)

• In left dominant hearts, LCA/circumflex occlusion carries greater risk of:

  • AV block
  • Larger territory of left ventricular involvement

• Coronary dominance affects surgical planning for bypass grafting and determines the haemodynamic consequences of individual vessel occlusion.

Key Fact

Whichever artery reaches the crux is the dominant artery. In the vast majority (~90%), this is the right coronary artery.