Yet Another Chest Pain

A 56-year-old obese man comes to the emergency department because of crushing chest pain that has been present for 3 hours. The pain radiates to his left arm and neck. He also complains of nausea. On physical examination, the patient is found to be sweating and his blood pressure is 164/122 mm Hg. Laboratory analysis reveals that his cardiac enzyme levels are elevated. His ECG is abnormal with ST-segment depression. Which of the following is the pathology underlying the correct diagnosis?

A. Coronary artery vasospasm caused by cigarettes and cocaine
B. Complete occlusion of the coronary arteries by a mural thrombus
C. Increased cardiac demand with coronary arteries that are greater than 75% occluded
D. Ischemic necrosis of 30% of the ventricular wall
E. Ischemic necrosis of 70% of the venricular wall

The correct answer is D. The patient has a subendocardial infarction, which is caused by ischemic necrosis of 75% occlusion of the coronary arteries by atherosclerosis. Although stable angina may produce slightly elevated cardiac enzyme levels, the clinical picture in this question is more typical of a myocardial infarction.

Answer E is not correct. Ischemic necrosis of >50% of the ventricular wall causes a transmural infarct. On ECG, there is a corresponding ST-segment elevation.

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