Left main coronary artery

Last revised by Daniel J Bell on 26 Apr 2021

The left main coronary artery (LMCA) or left coronary artery (LCA) is one of the two main coronary arteries that supply the heart with oxygenated blood.

The left main coronary artery is a branch of the ascending aorta, with its normal origin in the left aortic sinus, just superior to the aortic valve 1,2.

The left main coronary artery runs for 5-10 mm as it passes to the left and posterior to the pulmonary trunk before bifurcating 1,2.

Most hearts are right dominant, where the posterior descending artery (PDA) is supplied by the right coronary artery (RCA). However up to 20% of hearts may be left dominant, where the PDA is supplied by the LAD or LCx, or codominant, where a single or duplicated PDA is supplied by branches of both the RCA and LAD/LCx.

For a more in depth discussion of coronary dominance, see the article coronary arterial dominance.

Anatomical variations of the left main coronary artery (LMCA) include 3:

See main article: congenital coronary artery anomalies.

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