Shark Fin is an electrocardiographic sign of acute coronary occlusion. It is a unique ECG phenomenon consisting of complexes formed by the blurring together of QRS and T-wave as a result of extreme ST-Deviation. These complexes manifest in contiguous ECG leads corresponding with coronary anatomy, and represent transmural ischemia. Shark Fin Sign should be recognized based on its characteristic morphology, and confirmed by delineating the J-point using the technique described above. While there is a paucity of literature on the topic, the presence of this sign appears to be associated with a significant mortality, underscoring the critical importance of prompt recognition and emergency reperfusion.
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