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Multifocal atrial tachycardia

Alfred Buxton, MD
Section Editor
Leonard I Ganz, MD, FHRS, FACC
Deputy Editor
Brian C Downey, MD, FACC


Multifocal atrial tachycardia (MAT) is an arrhythmia that can be seen in a variety of clinical disorders [1]. In addition to a heart rate greater than 100 beats per minute, the characteristic electrocardiographic feature is variability in P wave morphology, with each unique P wave morphology felt to indicate a different site of atrial origin. Although this abnormality had been noted for many years during some types of atrial tachycardia, the term MAT became commonplace terminology in the late 1960s [2]. Patients with multiple P wave morphologies but a normal heart rate (60 to 100 beats per minute) are considered to have a wandering atrial pacemaker, since the heart rate does not meet criteria for a tachycardia. (See 'Terminology' below.)

This topic will review the definition, pathogenesis, etiology, and treatment of MAT in adults. Other tachycardias of atrial origin, as well as the discussion of this arrhythmia in children, are reviewed separately. (See "Focal atrial tachycardia" and "Atrial tachycardias in children" and "Atrioventricular nodal reentrant tachycardia" and "Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway" and "Overview of atrial fibrillation".)


As with any tachycardia, the heart rate in MAT exceeds 100 beats per minute. To distinguish MAT from other tachyarrhythmias of atrial origin, there should be organized atrial activity yielding P waves with three or more different morphologies. (See 'Clinical manifestations and diagnosis' below.)

Terminology — A number of authors have used the term "chaotic" to describe MAT [3-5]. However, chaos in modern usage in nonlinear dynamics and mathematics implies there is order in what appear to be random events [6]. A more accurate term for this arrhythmia is probably "multiform" as there is no proof that the arrhythmia is actually multifocal, although multifocal remains the commonly used term [1].

The tachycardic threshold for multifocal atrial tachycardia (MAT) has traditionally been set at 100 bpm, but a review of 60 patients with multifocal atrial arrhythmias found a stronger association between the incidence of COPD exacerbations and the diagnosis of MAT if a threshold of 90 bpm was used [7].

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Literature review current through: Nov 2017. | This topic last updated: Oct 12, 2017.
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