In an anterior MI, ST segment elevation is approximately how many millimeters?

• A. 5.0 mm
• B. 3.5 mm
• C. 4.5 mm
• D. 6.0 mm

Answer: (C)

ST segment elevation reflects transmural (full-thickness) ischemia from a STEMI. The amount of elevation tends to be larger when a large area of the heart is involved. Anterior myocardial infarctions involve the front wall of the left ventricle, supplied mainly by the LAD, so the injury current produces prominent ST elevation in the anterior chest leads (V1–V4). Because this area often sustains substantial injury, the elevation is typically sizable, around 4 to 5 millimeters, with 4.5 mm a common approximate value. This is why the best answer is about 4.5 mm.