ECG manifestations of ST segment elevation myocardial infarction, pericarditis, early repolarization syndrome, and Brugada syndrome are showcased in this chapter using real-life case examples. ECG features that differentiate these conditions from one another are presented. Localization of the culprit coronary artery lesion in ST segment elevation myocardial infarction using the 12-lead ECG is discussed. Where relevant, management issues with reference to current clinical practice guidelines are highlighted.