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HWN Suggests

Posterior MI Recognition

Isolated or true posterior myocardial infarction (PMI) is a rare entity occurring in about 4% of all ST-elevation myocardial infarctions (STEMIs). The standard ECG lead placement cannot directly illustrate what is occurring in the posterior heart. As a result, it is difficult to diagnose true PMIs. Isolated PMI is an indication for emergent reperfusion therapy and the absence of ST-segment elevation in the standard 12-lead ECG means the diagnosis is often missed.

Luckily, most PMIs occur in conjunction with an inferior or lateral STEMI, due to shared blood supply, making them less likely to be missed. Posterior infarction is associated with 15-20% of STEMIs. Isolated PMIs are often…

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 ECG Pointers: Posterior MI

Look for deep (>2mm) and horizontal ST-segment depression in the anterior leads and large anterior R-waves (bigger than the S-wave in V2). Posterior STEMI often occurs along with an inferior or lateral STEMI, but can also occur in isolation. A posterior ECG showing ST elevation of only 0.5mm in is diagnostic for posterior STEMI.

Articles of Interest

Posterior MI – Still Under-recognized

Posterior MI won’t produce ST elevation or Q waves on the 12 lead, but it can be recognized by Tall anterior R waves (especially new, and not secondary to RBBB/WPW/RVH), ST depression (including pseudonormalization) isolated to the anterior leads, especially horizontal, and often associated with upright T waves, Associated inferior or lateral hyperacute T waves or subtle elevation.

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StatPearls

Posterior myocardial infarction (PMI) accounts for a substantial number of cases of acute coronary syndrome (ACS); however, true PMI is often under-recognized, potentially leading to delays in treatment. PMI, like other acute myocardial infarction, is a true medical emergency with significant morbidity and mortality and requires urgent reperfusion therapy.