Question 18.3

A 75-year-old female admitted to the ICU with community-acquired pneumonia suddenly develops a tachycardia. Her 12 lead ECG is shown below (ECG 3).

a) What is the diagnosis? Justify your answer.
b) Name two co-existing diseases in critically ill patients where this condition is commonly seen.

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College Answer

 Multifocal atrial tachycardia
 Irregularly irregular rhythm rate > 100 bpm
 Multiple P wave morphologies

 Congestive cardiac failure


The above-displayed ECG comes from the LITFL page on multifocal atrial tachycardia.

The cardinal features are irregularity and a plethora of different P-wave morphologies.

You need to have

  • Tachycardia (HR >100)
  • Irregular rate
  • Variability in P wave morphology

The same findings with a normal heart rate does not qualify for MAT, because it's not tachycardia; you have to call that a "wandering atrial pacemaker".

The CICM question also asked for associated diseases.  In adults, MAT is almost uniformly associated with COPD. Not only are the atria stretched by pulmonary hypertension, but the proarrhythmic bronchodilators also make for an irritable myocardium.  In the paediatric population the differentials are more broad, including bronchiolitis, croup, bronchomalacia, etc.


Bradley, David J. "Multifocal atrial tachycardia." DEVELOPMENTS IN CARDIOVASCULAR MEDICINE 257 (2006): 135.

LiPSON, MANUEL J., and SHAPUR NAIMI. "Multifocal Atrial Tachycardia (Chaotic Atrial Tachycardia) Clinical Associations and Significance." Circulation 42.3 (1970): 397-407.