USMLE Step 3 - Question 6

A 74 year old male with diabetes mellitus and hypertension presents to the emergency department with chest pains. He is diagnosed with an anterior wall myocardial infarction and appropriate therapy is undertaken. Two months later he is seen by his cardiologist for dyspnea on exertion and lower extremity swelling. His ECG is below. What is his most likely diagnosis?

LV-Aneurysm

A. Pericarditis

B. Left ventricular aneurysm

C. Early repolarization

D. Cardiac tamponade

The patients clinical scenario and ECG findings are consistent with left ventricular (LV) aneurysm. A left ventricular aneurysm is a complication of an anterior wall myocardial infarction that can cause significant clinic issues including congestive heart failure, ventricular arrhythmias, left ventricular thrombus formation, and left ventricular rupture leading to cardiac tamponade. To diagnose a LV anuerysm on ECG there must be ST segment elevation anywhere from lead V1 to lead V4 and a history of a previous anterior wall myocardial infarction more than 6 weeks prior. The acute ECG changes seen with an anterior wall myocardial infarction can linger for up to 6 weeks, thus an LV aneurysm is not able to be diagnosed before then. Treatment of an LV aneurysm includes surgical resection known as the "Dorr procedure".

In pericarditis there would be diffuse ST segment elevation (concave upward) and PR depression. Early repolarization should "J point elevation" and occurs most commonly in young healthy people. Cardiac tamponade is not able to be diagnosed on ECG, although you may see low voltage due to the pericardial effusion dampening the ECG signal or "electrical alternans" due to the heart wobbling in the pericardial effusion causing every other beat to be dampened.