Multifocal Atrial Tachycardia (MAT)

Multifocal Atrial Tachycardia (MAT) Overview

  • A rapid, irregular atrial rhythm arising from multiple ectopic foci within the atria.
  • Most commonly seen in patients with severe COPD or congestive heart failure.
  • It is typically a transitional rhythm between frequent premature atrial complexes (PACs) and atrial flutter / fibrillation.

AKA “Chaotic atrial tachycardia”


Electrocardiographic Features

  • Heart rate > 100 bpm (usually 100-150 bpm; may be as high as 250 bpm).
  • Irregularly irregular rhythm with varying PP, PR and RR intervals.
  • At least 3 distinct P-wave morphologies in the same lead.
  • Isoelectric baseline between P-waves (i.e. no flutter waves).
  • Absence of a single dominant atrial pacemaker (i.e. not just sinus rhythm with frequent PACs).
  • Some P waves may be nonconducted; others may be aberrantly conducted to the ventricles.

There may be additional electrocardiographic features suggestive of COPD.


Clinical Relevance

  • Usually occurs in seriously ill elderly patients with respiratory failure (e.g. exacerbation of COPD / CHF).
  • Tends to resolve following treatment of the underlying disorder.
  • The development of MAT during an acute illness is a poor prognostic sign, associated with a 60% in-hospital mortality and mean survival of just over a year. Death occurs due to the underlying illness; not the arrhythmia itself.

Mechanism

Arises due to a combination of factors that are present in hospitalised patients with acute-on-chronic respiratory failure:

  • Right atrial dilatation (from cor pulmonale)
  • Increased sympathetic drive
  • Hypoxia and hypercarbia
  • Beta-agonists
  • Theophylline
  • Electrolyte abnormalities: Hypokalaemia and hypomagnesaemia (e.g. secondary to diuretics / beta-agonists)

The net result is increased atrial automaticity.


ECG Examples

Example 1
Multifocal Atrial Tachycardia (MAT)
Multifocal atrial tachycardia

Multifocal atrial tachycardia:

  • Rapid irregular rhythm > 100 bpm.
  • At least 3 distinctive P-wave morphologies (arrows).

Example 2
Multifocal Atrial Tachycardia (MAT) COPD 2

MAT with additional features of COPD:

  • Rapid, irregular rhythm with multiple P-wave morphologies (best seen in the rhythm strip).
  • Right axis deviation, dominant R wave in V1 and deep S wave in V6 suggest right ventricular hypertrophy due to cor pulmonale. 

Related Topics


LITFL Further Reading


Advanced Reading


ECG LIBRARY 700

ECG LIBRARY

Electrocardiogram

Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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