Which ECG finding is most specific for posterior wall myocardial infarction?
- A ST elevation in aVR
- B Pathological Q waves in V5–V6
- C Tall R wave and ST depression in V1–V2 ✓
- D Left bundle branch block
Correct answer: C. Tall R wave and ST depression in V1–V2
Explanation
Posterior MI is a mirror image of anterior MI in the anteroseptal leads. The characteristic changes are tall broad R waves (mirror of posterior Q waves), upright T waves, and ST depression in V1–V2, which is the mirror image of posterior ST elevation. Posterior leads (V7–V9) show ST elevation directly. ST elevation in aVR suggests left main or proximal LAD occlusion. Q waves in V5–V6 indicate lateral infarction.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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