A 59-year-old man with a history of hypertension and hyperlipidemia presents with 1 hour of substernal chest pressure

 A 59-year-old man with a history of hypertension and hyperlipidemia presents with 1 hour of substernal chest pressure rated an 8 on a scale of 1 to 10 with radiation down the left arm and associated with diaphoresis. Initial vital signs are notable for a blood pressure (BP) of 92/64 mmHg and a heart rate (HR) of 92 beats/min. His electrocardiogram (ECG) is shown below

What is the most likely diagnosis?

A. Anterior ST-elevation myocardial infarction

B. Inferior ST-elevation myocardial infarction

C. Pericarditis

D. ST changes not meeting specific ischemia criteria; additional ECGs should be obtained.

ANSWER: 

The correct answer is: B. 

Discussion

Inferior ST-elevation myocardial infarction. The patient has ST elevations ≥1 mm in two contiguous leads (III, aVF), meeting criteria for ST-elevation myocardial infarction. The presence of ST depressions in leads I and aVL reflects reciprocal changes, while the presence of ST depressions in leads V2 and V3 may indicate posterior myocardial ischemia. In addition, there are T-wave inversions in V4 to V6. The patient meets ST-elevation myocardial infarction criteria and requires urgent revascularization. The absence of anterior (V3-V4) elevations makes anterior involvement unlikely, and the territorial nature of the ECG changes argues against pericarditis.