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Shark Sighting on ECG – STEMI Pattern You Need to Know

January 11, 2023

Written by Clark Strunk

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Massive ST segment elevation on ECG (so called ‘shark fin’ pattern, see below) is indicative of severe myocardial injury and is associated with increased risk of ventricular arrhythmia, cardiogenic shock, and death.

Why does this matter?
The shark fin pattern is an infrequent ECG pattern that is associated with high in-hospital mortality and requires aggressive intervention. Although there are several etiologies of this pattern, immediate angiography is necessary to rule out an acute coronary occlusion.

Some-fin we all must recognize on the ECG…
In this JAMA IM case report, an individual in their 50s presented with diabetic ketoacidosis, acute kidney injury, rhabdomyolysis, and acute myocardial injury. The ECG, shown below, demonstrated massive ST elevation in the mid and lateral precordial leads. Cardiac catheterization demonstrated no culprit vessel, and echocardiography demonstrated akinesis of the wall segments corresponding to the ECG changes, which in this metabolic background was highly suggestive of takotsubo cardiomyopathy.

From cited article

The shark fin morphology can be conceptualized as simply massive ST elevation taking on the morphology seen in the ECG above. Although typically associated with an acute coronary occlusion, this pattern can be more generally thought of as indicating ongoing myocardial injury from a variety of etiologies, as this case exemplifies. The shark fin pattern is discussed as a separate entity because the magnitude and morphology of the ST elevation is not what we typically see (only 1.4% of STEMIs take on this morphology). It can often be mischaracterized when the ST elevation is thought to instead be part of a widened QRS complex, and the prognosis and treatment implications of this pattern are unique.

Shark Sighting in an Electrocardiogram. JAMA Intern Med. 2022 Dec 12. doi: 10.1001/jamainternmed.2022.5061. Epub ahead of print.

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