Identifying the location of the lesion within the coronary artery is important for the purposes of risk stratification. Start by locating the primary area of myocardium involved.

Primary anterior process:
Aside from an acute occlusion of the left main coronary artery, occlusion of the proximal left anterior descending coronary artery conveys the greatest adverse outcomes. Four ECG signs indicate proximal LAD occlusion:

1. ST elevation >1 mm in either lead I, aVL, or both
2. New right bundle branch block
3. New left anterior fascicular block
4. New first degree A-V block

Primary inferior process:
Nearly 50% of patients with IMI will have distinguishing features that may produce complications or adverse outcomes unless successfully managed. These include:

1. Precordial ST segment depression in V1-3, suggestive of concomitant posterior wall involvement
2. Right ventricular injury or infarction, which identifies a proximal RCA lesion,
3. A-V block, which conveys a greater amount of involved myocardium, and
4. The sum of ST segment depression in leads V4-6 which exceeds that of the sum of ST segment depression in leads V1-3 (which suggests multivessel disease).

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