Which finding is characteristic of multifocal atrial tachycardia?

Multifocal atrial tachycardia (MAT) is characterized by a rapid heart rate that is typically greater than 100 beats per minute. This arrhythmia arises from multiple ectopic foci in the atria, which leads to the production of P waves that vary in shape and morphology. The heart rate aspect is significant in identifying MAT, as it generally indicates a higher frequency of atrial activity due to these ectopic foci.

The presence of a heart rate above 100 bpm in MAT is particularly characteristic, aligning with its classification as a tachyarrhythmia. It is important to recognize that this defining feature helps differentiate MAT from other types of atrial arrhythmias, where heart rates may vary significantly or fall below this threshold. Therefore, the heart rate being greater than 100 bpm is a key indicator of multifocal atrial tachycardia, affirming the diagnosis.