ST-segment depressions in the anterior ECG leads most strongly suggest which diagnosis?

ST-segment depressions in the anterior ECG leads most strongly suggest which diagnosis?

• A. Anterior MI
• B. Aortic dissection
• C. Posterior MI
• D. Pericarditis

Answer: (C)

ST-segment depression in the front-facing chest leads is a reciprocal change associated with injury to the back wall of the heart. When the posterior wall is infarcted, the electrical current moves toward the posterior surface and away from the anterior leads, so the ECG shows ST-segment depression in those anterior leads (often with large R waves in the same leads). This pattern is a classic clue pointing to a posterior myocardial infarction, and it’s usually confirmed by looking at posterior-directed leads (such as V7–V9) that show ST elevation. Other conditions don’t produce this reciprocal pattern. An anterior myocardial infarction typically produces ST elevations in the anterior leads, not depressions. Aortic dissection presents with acute severe chest or back pain and may cause various nonspecific ECG changes, but not a characteristic reciprocal ST-depression pattern in the anterior leads. Pericarditis usually causes diffuse ST elevations with PR depressions rather than localized ST depressions in the anterior leads. So, the presence of ST-segment depressions in the anterior leads most strongly points to a posterior myocardial infarction.

ST-segment depression in the front-facing chest leads is a reciprocal change associated with injury to the back wall of the heart. When the posterior wall is infarcted, the electrical current moves toward the posterior surface and away from the anterior leads, so the ECG shows ST-segment depression in those anterior leads (often with large R waves in the same leads). This pattern is a classic clue pointing to a posterior myocardial infarction, and it’s usually confirmed by looking at posterior-directed leads (such as V7–V9) that show ST elevation.

Other conditions don’t produce this reciprocal pattern. An anterior myocardial infarction typically produces ST elevations in the anterior leads, not depressions. Aortic dissection presents with acute severe chest or back pain and may cause various nonspecific ECG changes, but not a characteristic reciprocal ST-depression pattern in the anterior leads. Pericarditis usually causes diffuse ST elevations with PR depressions rather than localized ST depressions in the anterior leads.

So, the presence of ST-segment depressions in the anterior leads most strongly points to a posterior myocardial infarction.