Sharpen YOur Calipers - Dr. Littmann

What is STEMI without STE?

1. Patients presenting with acute chest pain may have clinical STEMI (acute total thrombotic occlusion of a large coronary artery) but no obvious ST-segment elevation in the ECG
2. This occurs with STEMI locations that are not well represented by conventional ECG leads
3. Such patients are at high for not receiving timely reperfusion therapy and for having poor outcomes
4. Easily memorizable ECG signs can help raise awareness of the possibility of STEMI without STE
5. If suspected, placing exploring electrodes to the area of interest can quickly uncover the STEMI

 
Posterolateral or High Posterior MI

1. The most common type of missed STEMI
2. Almost always due to acute occlusion of the LCX
3. May involve the posterior papillary muscle and can cause severe mitral regurgitation
4. Earliest ECG sign: ST depression in the anterior chest leads (mirror image of posterior ST elevation)
5. Frequent associated findings: subtle Q waves or subtle ST elevation in the inferior or lateral leads
6. Can be uncovered by placing exploring electrodes to the back (V7-V8-V9)

 
High Lateral MI

1. The second most commonly missed STEMI
2. Almost always due to acute occlusion of the first diagonal branch of the LAD (LAD-D1)
3. Fortunately usually small
4. Earliest ECG sign: ST elevation in leads I, aVL and V2, but not in V1 or V3, and ST depression in III and aVF
5. With the conventional 4x3 lead display format, the spacing of ST deviation resembles the shape of the South African flag (the “South African Flag Sign”)
6. Can be uncovered by placing the V4-V5-V6 ECG leads 1 and 2 interspaces higher

 
RV infarct

1. Almost always due to acute occlusion of the proximal RCA
2. Almost always associated with acute inferior STEMI
3. Recognition of RV infarct, therefore, is now less important because code STEM is usually called anyway for the inferior MI
4. Recognition can be important, however, if the ST elevation in the inferior leads is subtle or nondiagnostic
5. Clues to suspect RV MI:
   1. Inferior STEMI with marked ST depression in I and aVL (left leads)
   2. Inferior STEMI with ST elevation in V1 only but not in V2
6. Can be uncovered by placing right-sided chest leads
7. If inferior STEMI has been diagnosed, there is no need to waste time to record right-sided chest leads
8. Suspected RV MI:
   1. Use caution with vasodilators (nitrates)
   2. Consider IV fluids for hypotension with JVD

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