Multifocal Atrial Arrhythmia

Multifocal Atrial Rhythm (MAR) and Multifocal Atrial Tachycardia (MAT)

ECG Recognition:

• Variable P-wave morphology of at least 3 different configurations.
• Irregular PP, RR and PR intervals.
• The change in P wave morphology is not gradual in contrast to wandering atrial pacemaker (WAP).
• The rate is less than 100 bpm for multifocal atrial rhythm (MAR). If the rate is more than 100 bpm, the rhythm is called multifocal atrial tachycardia (MAT) or chaotic atrial tachycardia.
• Another name for MAR is multifocal PAC.
• Some of the conducted P waves are wide because one of the bundle branches is still in refractory period. The electrical impulse is blocked on one of the bundle branches. This delay the cardiac conduction. Thereby creating a wide QRS. This intermittent block is called aberrancy. 

Multifocal atrial rhythm (MAR)/ multifocal atrial tachycardia (MAT). This is an irregularly irregular rhythm with multiple P wave morphologies. The PP, RR and PRI varies. The rate varies from 60 to 150 bpm. 

Multifocal Atrial Tachycardia with a bundle branch block. This is an irregularly, irregular rhythm with several different P wave morphology and variable PR interval. The QRS is wide (~0.12 sec). The rate is about 120-130 bpm using the six-second method. 

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