Both of these patients presented with chest pain.  What do you think of the ECGs?

For the answer, go to the free pdf of this paper I authored in Annals of Emergency Medicine, p. 52 (the 8th page of the paper).   There is a full explanation of the formula which helps to differentiate these two entities. 

There is an online excel spreadsheet on the right sidebar of the front page of this blog which can be used to calculate the formula value and help you to assess your patient’s ECG.

The picture below shows where to find the online calculator.  It is important to read the limitations in red above the calculator: