Long-term Outcomes in Individuals With Prolonged PR Interval or First-Degree Atrioventricular Block

Abstract

Prolongation of the electrocardiographic PR interval, conventionally known as first-degree atrioventricular block (AVB) when the PR interval exceeds 200 milliseconds, is frequently encountered in clinical practice.^1-4 The PR interval is determined by the conduction time from the sinus node to the ventricles and thus integrates information about a number of sites in the conduction system of the heart. First-degree AVB may result from conduction delay in the atrium, atrioventricular node, and/or His-Purkinje system. The atrioventricular node is the site most commonly involved in adults, although more than 1 site of conduction delay is often present.⁵