This 80-year-old man with known ischemic cardiomyopathy presents to the Emergency Department with severe low-output failure, hypotension, and hypoxemia. He denies any chest pain:

• Sinus rhythm, with a run of non-sustained atrial tachycardia, ventricular rate 80/min
• First degree AV block
• Nonspecific Intraventricular Block
• Septal infarction, age undetermined
• Very tall, symmetrical, peaked T waves in the chest leads, consider hyperkalemia

On bloodwork, her serum potassium was found to be 8.3 mmol/L (normal = 3.5-5.1 mmol/L)

A frequently asked question is: how do these tall T waves compare with those found in hyperacute ischemia/infarction? The answer to this is that the “hyperacute T waves” of ischemia/infarction are tall and symmetrical, but typically broad-based, not narrow and pointed (see ECG ID: E552 for an example of hyperacute T waves in the early stage of an acute anterior infarction). 

In this severely ill patient with an ischemic cardiomyopathy, the possibility of “hyperacute T waves” was also considered in the differential diagnosis.