Damage to the left atrium and the posterior portion of the left ventricle is most consistent with occlusion of which artery?

• A. Right coronary artery
• B. Circumflex artery
• C. Left anterior descending artery
• D. Posterior descending artery

Answer: (B)

Understanding coronary artery territories helps explain which heart structures are affected when an artery is blocked. The left circumflex artery gives off branches that supply the left atrium and the posterior (diaphragmatic) wall of the left ventricle. If this artery is occluded, those regions lose blood supply and can be damaged. The right coronary artery mainly supplies the right atrium and much of the inferior heart, the left anterior descending artery runs along the anterior left ventricle and the interventricular septum, and the posterior descending artery supplies the posterior ventricular region (its origin varies with dominance). Since the damage described involves the left atrium and the posterior left ventricular wall, the artery most consistent with that pattern is the left circumflex.