A 39-year-old man is presenting to the Emergency department with a left renal colic and complaints of atypical left chest pain:

• Sinus arrhythmia
• Early repolarization (a normal variant)

There is ST elevation with upward concavity that is marked in the chest leads and mild in the limb leads. The T waves are tall (the ratio of the voltage of the T wave to the voltage of the ST elevation is >4:1). These findings are in keeping with “early depolarization“, a normal variant and help to distinguish it from pericarditis, in which the ST is more diffusely elevated and the T eaves less tall. Early depolarization is more frequently seen in young men.

Link to reference article: Ginzton LE, Laks Michael, The differential diagnosis of acute pericarditis from the normal variant: new electrocardiographic criteria. Circulation 65:1004,1982  http://circ.ahajournals.org/cgi/reprint/65/5/1004