The document discusses electrocardiogram (ECG) patterns associated with cardiac chamber enlargement, specifically right atrial enlargement (RAE) and left atrial enlargement (LAE). RAE is suggested by a tall, peaked P wave in leads II, III, AVF and a positive P wave in V1. LAE results in prolongation of the left atrial component of the P wave, increased posterior deviation of the left atrial vector, and left axis deviation of the P wave. The diagnostic accuracy of ECG findings for chamber enlargement is limited but can provide clues when correlated with imaging studies.