A 58-year-old male presents with acute central chest pressure radiating to the left arm. ECG demonstrates ST-segment elevation of 2.5 mm in leads II, III, and aVF. Which coronary artery is most likely occluded?

Answer and explanation

Correct answer: C. Right coronary artery (RCA)

  1. Step 1: Leads II, III, and aVF correspond to the inferior myocardial wall.
  2. Step 2: In approximately 85% to 90% of individuals with right-dominant coronary circulation, the inferior wall and posterior descending artery are supplied by the right coronary artery (RCA).
  3. Step 3: Therefore, acute inferior STEMI is most commonly caused by acute thrombotic occlusion of the RCA.
Answer
Right coronary artery (RCA).
Why not the others: 'Left anterior descending artery (LAD)' supplies the anterior and septal myocardium (leads V1-V4); 'Left circumflex artery (LCx)' supplies the lateral wall (leads I, aVL, V5-V6); 'Left main coronary artery' occlusion produces widespread ischemic changes with ST elevation in aVR.

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