PR prolongation is defined primarily as delayed conduction through the AV node, but can also signify delayed electrical impulse propagation through any part of the conduction system. The prevalence of PR prolongation ranges from 1% to 5% in patients younger than 50 years, with increasing prevalence, after the sixth decade of life and in patients with organic heart disease. Contemporary studies have documented increased risk of atrial arrhythmias, heart failure, and mortality in patients with PR prolongation. Future studies are needed to more accurately risk stratify elderly patients with PR prolongation who may be at increased risk of adverse outcomes.