Anterior Myocardial Infarction LITFL ECG Library Diagnosis

Clinical Relevance of Anterior Myocardial Infarction

Anterior STEMI results from occlusion of the left anterior descending artery (LAD). Anterior myocardial infarction carries the worst prognosis of all infarct locations, mostly due to larger infarct size.

A study comparing outcomes from anterior and inferior infarctions (STEMI + NSTEMI) found that on average, patients with anterior MI had higher incidences of in-hospital mortality (11.9 vs 2.8%), total mortality (27 vs 11%), heart failure (41 vs 15%) and significant ventricular ectopic activity (70 vs 59%) and a lower ejection fraction on admission (38 vs 55%) compared to patients with inferior MI.

In addition to anterior STEMI, other high-risk presentations of anterior ischaemia include left main coronary artery (LMCA) occlusion, Wellens syndrome and De Winter T waves.

NB. The magnitude of the reciprocal change in the inferior leads is determined by the magnitude of the ST elevation in I and aVL (as these leads are electrically opposite to III and aVF), hence may be minimal or absent in anterior STEMIs that do not involve the high lateral leads.

The nomenclature of anterior infarction can be confusing, with multiple different terms used for the various infarction patterns. The following is a simplified approach to naming the different types of anterior MI.

The precordial leads can be classified as follows:

The different infarct patterns are named according to the leads with maximal ST elevation:

(NB. While these definitions are intuitive, there is often a poor correlation between ECG features and precise infarct location as determined by imaging or autopsy. For an alternative approach to the naming of myocardial infarctions, take a look at this 2006 article from Circulation)

ECG Examples

Hyperacute Anteroseptal STEMI

Example 2(b)

A ECG of the same patient taken around 40-50 minutes later:

Example 3

Extensive Anterolateral STEMI (acute)

Extensive Anterior STEMI (acute)

Prior Anteroseptal / Lateral MI

Extensive anterior MI (tombstoning pattern)

Anterior-inferior STEMI

The site of LAD occlusion (proximal versus distal) predicts both infarct size and prognosis.

[This great diagram was originally featured on The Radiology Assistant follow the link for a more detailed review of coronary artery anatomy.]

Signs of basal septal involvement:

Signs of high lateral involvement:

ST elevation in aVR of any magnitude is 43% sensitive and 95% specific for LAD occlusion proximal to S1. Right bundle branch block in anterior MI is an independent marker of poor prognosis; this is due to the extensive myocardial damage involved rather than the conduction disorder itself.

This patients ECG shows several signs of a very proximal LAD occlusion (Ostial LAD occlusion (septal STEMI)):

This patient came in post VF arrest and was taken straight to the cath lab where he was found to have a complete ostial occlusion of his LAD.

Example 9

Acute anteroseptal STEMI with STE maximal in V1-4. The following signs of proximal LAD occlusion are present:

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Related Topics

LAD Occlusion Syndromes

Other STEMI Patterns

References

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Anterior Myocardial Infarction LITFL ECG Library Diagnosis