Multifocal atrial tachycardia

Definition

An irregular atrial tachycardia defined by at least 3 distinct P-wave morphologies with varying PP, PR, and RR intervals and an atrial rate above 100 bpm; the changing P waves are usually attributed to multiple atrial foci, although the mechanism is not firmly established. It is most often seen in older, seriously ill patients, especially those with chronic lung disease, and can be mistaken for atrial fibrillation, but discrete P waves with an isoelectric baseline between them are present.

Clinical noteDiscrete P waves with an isoelectric baseline distinguish it from atrial fibrillation.