Which ECG leads provide information about the functioning of the right coronary artery (RCA)?

Which ECG leads provide information about the functioning of the right coronary artery (RCA)?

• A. I, aVL, V5
• B. V1-V3
• C. II, III, and aVF
• D. aVR, V4-V6

Answer: (C)

The key idea is that the ECG leads that view the inferior surface of the heart reflect the territory supplied by the right coronary artery in most people. The inferior wall is seen in the limb leads II, III, and aVF, so ischemia or infarction in the RCA territory produces noticeable changes there. In contrast, the other leads map to the anterior/septal (V1–V3) and lateral (I, aVL, V5–V6) surfaces, which are less indicative of RCA involvement. Keep in mind that in most individuals the RCA supplies the inferior wall (and often the AV node), so ST changes in II, III, and aVF are the best clues to RCA-related issues.