Sharkfin OMI

A sharkfin OMI is one that is commonly missed or misunderstood as a wide complex tachycardia or metabolic disturbance due to the huge ST elevations. These OMIs have such large ST elevation that it may appear to be a part of the QRS complex, making identification of the J point difficult. Sometimes, these are called 'Giant R wave OMIs', though this is not an accurate term as the ST segment elevation is not actually a part of the R wave. It is important to look throughout the EKG to identify the J point (some leads are usually easier than others) and, therefore, identify the ST elevation. Because of the worse prognosis for every mm ST elevation, these patients commonly die before or shortly after cath lab arrival. These are commonly found with proximal LAD occlusions and may have a RBBB, LAFB, or bifascicular block (with an even worse prognosis).

The J point can be identified where the downslope from the QRS complex changes angles. This will result in a less sharp angle going downward (the angle flattens out a bit) from the ST segment.

Sharkfin OMI (see sharkfin best in aVL)

Same EKG but J point marked

Sharkfin OMI

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