"The electrocardiogram is used frequently in the emergency department (ED) and other acute care settings; numerous presentations may require a 12-lead electrocardiogram. For instance, the most frequent indication for ECG performance in the ED is the presence of chest pain; other complaints frequently involving ECG analysis include dyspnea and syncope. Physicians obtain an ECG in the ED in the evaluation of suspected acute coronary syndrome, pulmonary embolism, intentional medication overdose, among other situations; the ECG also plays a major role in various diagnostic strategies, such as the "rule-out myocardial infarction" protocol"--