Acute Inferior Wall Myocardial Infarction ECG Characteristics

One of the key diagnostic tools for identifying acute inferior wall myocardial infarction is the electrocardiogram (ECG). The changes typically appear in the inferior leads — specifically leads II, III, and aVF. These leads provide a clear view of the heart's electrical activity in the affected area. Recognizing these ECG patterns is essential for timely treatment and improved patient outcomes.

Key ECG Features of Acute Inferior Wall Myocardial Infarction

1. Acute Injury-Related Conduction Delay

An early sign of acute myocardial infarction is the appearance of an injury-related conduction delay. This is often seen as a widened R wave and prolonged ventricular activation time. The QRS complex may extend beyond 0.12 seconds, indicating delayed depolarization in the affected myocardial tissue.

2. ST-Segment Elevation in Inferior Leads

One of the most characteristic findings is ST-segment elevation in leads II, III, and aVF. This elevation typically presents as a convex upward (or "tombstone") pattern, forming a single-phase morphology. This distinct shape helps differentiate myocardial injury from other causes of ST elevation, such as early repolarization or pericarditis.

3. Hyperacute T Waves

In the early stages of infarction, T waves in the affected leads may become tall, peaked, and symmetric — a phenomenon known as hyperacute T waves. This change can resemble the ECG appearance of hyperkalemia, so it's important to correlate these findings with clinical symptoms and lab results to avoid misdiagnosis.

4. Development of Pathological Q Waves

As the infarction progresses, pathological Q waves typically develop in the same inferior leads (II, III, aVF). These Q waves are usually deep and wide, often exceeding 0.04 seconds in duration. Their presence indicates irreversible myocardial damage and is a key diagnostic criterion for established myocardial infarction.

Understanding these ECG changes is crucial for clinicians managing patients with suspected acute coronary syndromes. Early recognition of these patterns can significantly improve outcomes through prompt reperfusion therapy and appropriate risk stratification.