When does the wandering pacemaker rhythm become multifocal atrial tachycardia (MAT)?

When does the wandering pacemaker rhythm become multifocal atrial tachycardia (MAT)?

• A. When the atrial rate goes above 120 bpm
• B. When the atrial rate goes above 100 bpm
• C. When the P wave shape becomes abnormal
• D. When the ventricular rate becomes irregular

Answer: (B)

In the context of atrial rhythms, wandering pacemaker is characterized by varying P wave morphology and an atrial rate typically less than 100 beats per minute. When the atrial rate rises above 100 beats per minute, the rhythm transitions to multifocal atrial tachycardia (MAT). This higher rate, which is typically over 100 bpm, indicates a more active and chaotic firing of multiple ectopic atrial pacemakers, rather than just the wandering pacemaker activity at lower rates.

MAT is particularly relevant in clinical scenarios where it indicates underlying conditions such as pulmonary disease or electrolyte imbalances. The shift to a rate above 100 bpm, while still maintaining varying P wave shapes, signifies this transition into MAT. Therefore, the defining characteristic of this transition is the increase in atrial rate, making it the crucial factor in distinguishing MAT from the wandering pacemaker rhythm.