Which ECG leads are used to diagnose an anterolateral myocardial infarction?

• A. V5 and V6
• B. V1 and V2
• C. II and III
• D. I and aVL

Answer: (A)

Anterolateral myocardial infarction involves the front-left side of the heart, so ECG changes show up best in leads that view the lateral wall. The left precordial leads V5 and V6 specifically project the lateral portion of the left ventricle, making ST-segment elevations in these leads a classic indicator of anterolateral injury. These leads are often used together because they provide contiguous, complementary views of the same territory, and ST elevations in them strongly support an anterolateral infarction.

Leads focusing on other regions don’t map to the anterolateral wall as directly: V1–V2 look at the septum, II–III look at the inferior wall, and I with aVL reflect lateral view but aren’t as specifically aligned with the anterolateral region as V5 and V6. In practice, detecting ST elevations in V5 and V6 (often alongside I and aVL) helps confirm an anterolateral MI.