Reddit reviews Introduction to 12-Lead ECG: The Art of Interpretation

I used Thomas Garcia's 12-Lead ECG: The Art of Interpretation. It goes above and beyond what you are required to know into stuff that is useful to know. It also breaks it down and gives tons of real world examples. This is how I learned EKGs. It might be better to start with something simpler, like Dale Dubin's Rapid Interpretation of EKG's, but I would make sure you know more than the simplistic version presented there.