posterolateral myocardial infarction

Posterolateral Myocardial Infarction: A Rare but Challenging Diagnosis

Posterolateral myocardial infarction (PMI) is a type of heart attack that affects the posterior and lateral walls of the left ventricle. This condition is relatively rare compared to anterior and inferior infarctions, with an incidence rate of 3-7% [9]. PMI can be challenging to diagnose due to the absence of ST-segment elevation on a standard 12-lead ECG [6].

ECG Findings

The ECG findings of an acute posterolateral wall MI include:

• ST segment depression (not elevation) in the septal and anterior precordial leads (V1-V4) [3]
• Tall R waves in V1 and V2, indicating posterior infarction [14]

Clinical Presentation

Patients with PMI may present with classic symptoms of a heart attack, such as chest pain and shortness of breath. However, the clinical presentation can be variable and not always easy to diagnose, even for cardiologists [2].

Co-occurrence with Other Infarctions

PMI commonly co-occurs with inferior or inferolateral MI, but when in isolation, it represents a diagnostic challenge. Posterior wall myocardial infarction occurs when circulation becomes disrupted to the posterior heart, and it is essential to consider this condition in patients presenting with atypical symptoms [10].

Importance of Accurate Diagnosis

Accurate diagnosis of PMI is crucial for appropriate treatment and management. Misdiagnosis can lead to delayed or inadequate treatment, which can worsen outcomes. Therefore, it is essential for healthcare providers to be aware of the ECG findings and clinical presentation of PMI.

References:

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The differential diagnosis for posterolateral myocardial infarction (PMI) involves considering various conditions that can present with similar symptoms and electrocardiographic (ECG) changes.

Conditions to Consider:

• Posterior wall myocardial infarction: This is a rare entity, accounting for only 4% of all ST-elevation myocardial infarctions (STEMIs). It occurs when circulation becomes disrupted to the posterior heart.
• Inferior or inferolateral MI with posterior extension: When an inferior or lateral infarct extends to the posterior wall, it can mimic a posterolateral MI. This is often associated with a larger area of myocardial damage and increased risk of left ventricular dysfunction and death.
• Acute pericarditis: This condition can present with chest pain and ECG changes similar to those seen in PMI.
• Stable angina: While less likely, stable angina can also cause chest pain that may be mistaken for a myocardial infarction.

ECG Findings:

• Tall R waves in leads V1-V3: These can represent posterior Q-waves or upright T-wave inversions.
• ST segment elevation in leads V7-V9: This is a key finding in PMI, but it's essential to note that ST segment elevation can also be seen in other conditions.

Clinical Considerations:

• History and physical exam: A thorough history and physical examination are crucial in narrowing the differential diagnosis.
• Other diagnostic tests: Additional tests such as echocardiography or cardiac biomarkers may be necessary to confirm the diagnosis.

It's essential to consider these factors when differentially diagnosing posterolateral myocardial infarction. A detailed understanding of the ECG findings and clinical presentation can help guide further evaluation and management.

References:

• [1] Isolated or true posterior myocardial infarction (PMI) is a rare entity occurring in about 4% of all ST-elevation myocardial infarctions (STEMIs).
• [2] The differential for tall R-waves in leads V1-V3 should include the possibility that they represent posterior Q-waves or that upright T-waves may actually be posterior T-wave inversions.
• [3] Posterior leads can show more typical ECG changes in PMI, such as ST segment elevation in leads V7-V9.