Inferior Wall ST Segment Elevation Myocardial Infarction (MI) ECG Review

An inferior wall myocardial infarction — also known as IWMI, or inferior MI, or inferior ST segment elevation MI, or inferior STEMI — occurs when inferior myocardial tissue supplied by the right coronary artery, or RCA, is injured due to thrombosis of that vessel. When an inferior MI extends to posterior regions as well, an associated posterior wall MI may occur.

The ECG findings of an acute inferior myocardial infarction include the following:

  1. ST segment elevation in the inferior leads (II, III and aVF)
  2. Reciprocal ST segment depression in the lateral and/or high lateral leads (I, aVL, V5 and V6)

Inferior_MI_Angiogram

Note: If the reciprocal ST segment depressions are not present, consider alternative causes of ST segment elevation, such as pericarditis.

An inferior MI can have multiple potential complications and can be fatal. See the STEMI Topic Review for more detail on these complications and a detailed discussion on treatment.

ECG Examples:

References:
1. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
2. Surawicz B, et al. AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram. Circulation. 2009;doi:10.1161/CIRCULATIONAHA.108.191095.