What is a significant finding when interpreting PACs on EKG?

In the context of interpreting premature atrial contractions (PACs) on an electrocardiogram (EKG), the significant finding is the presence of early P waves. PACs occur when an atrial ectopic focus fires before the next scheduled sinus impulse, leading to a P wave that appears earlier than expected in the cardiac cycle. This P wave can often have a different morphology than that of the standard sinus P waves, indicating its origin from an abnormal site in the atria.

The early P wave is crucial because it identifies the characteristic premature contraction originating in the atria, distinguishing PACs from other arrhythmias. Observing these early P waves on an EKG provides essential insight into the underlying rhythm disturbances and helps guide further evaluation and management of the patient's condition.