This 55-year-old diabetic man with a two year history of mild angina is brought to the Emergency Department three hours after the onset of constrictive central anterior chest pain:

• Sinus rhythm
• Incomplete right bundle branch block (iRBBB)
• ST elevation and tall T waves in V1-V4 (anterior injury pattern with hyperacute T waves)
• Acute anterior infarction

Hyperacute T waves can be seen in the early stages of myocardial infarction. They are tall, often bulky and symmetrical, and usually associated with ST elevation. They are localized in the area of infarction and are transient; although persistent hyperacute T waves with ST depression have been described in the precordial leads of patients with occlusion of the left anterior descending artery.

The following ECG was recorded 12 hours later in the Coronary Care Unit:

• Sinus rhythm
• Left axis deviation
• Acute Inferior Infarction
• Acute anterior infarction 

The following ECG was recorded 38 hours after the initial ECG:

• Sinus rhythm
• Left axis deviation
• Evolutionary changes of recent inferior and anterior infarction