How is posterior MI recognized on a standard 12-lead ECG?

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Multiple Choice

How is posterior MI recognized on a standard 12-lead ECG?

Posterior myocardial infarction shows up as reciprocal changes on the standard 12-lead ECG because the infarct is on the back wall of the heart. The injury current directed toward the posterior wall makes the anterior leads look like ST segments are depressed and tall R waves appear in V1–V2, rather than seeing the classic ST elevations directly in those leads. If you place posterior leads (V7–V9), you can directly see ST elevations in the posterior region, confirming the infarct. So the pattern to recognize is ST depression and a prominent R wave in the anterior leads, with possible ST elevations in posterior leads. This is not typically described by prominent U waves, new left bundle branch block, or isolated ST depression without the posterior corroboration.

Posterior myocardial infarction shows up as reciprocal changes on the standard 12-lead ECG because the infarct is on the back wall of the heart. The injury current directed toward the posterior wall makes the anterior leads look like ST segments are depressed and tall R waves appear in V1–V2, rather than seeing the classic ST elevations directly in those leads. If you place posterior leads (V7–V9), you can directly see ST elevations in the posterior region, confirming the infarct. So the pattern to recognize is ST depression and a prominent R wave in the anterior leads, with possible ST elevations in posterior leads. This is not typically described by prominent U waves, new left bundle branch block, or isolated ST depression without the posterior corroboration.

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