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”
- 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.
- 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.
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
- Electrolyte abnormalities: Hypokalaemia and hypomagnesaemia (e.g. secondary to diuretics / beta-agonists)
The net result is increased atrial automaticity.
Multifocal atrial tachycardia:
- Rapid irregular rhythm > 100 bpm.
- At least 3 distinctive P-wave morphologies (arrows).
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.
LITFL Further Reading
- ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis – ECG interpretation in clinical context
- ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
- 100 ECG Quiz – Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS – the best of the rest
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric
- Wagner GS. Marriott’s Practical Electrocardiography 12e
- Chan TC. ECG in Emergency Medicine and Acute Care
- Rawshani A. Clinical ECG Interpretation
- Mattu A. ECG’s for the Emergency Physician
- Hampton JR. The ECG In Practice, 6e