Which arrhythmia may present with a "stepwise" increase in heart rate?

The presence of a "stepwise" increase in heart rate is most commonly associated with paroxysmal atrial tachycardia (PAT). This arrhythmia is characterized by sudden episodes of rapid heart rate that can begin and end abruptly. During an episode, the heart rate can gradually accelerate in a stepwise manner as the ectopic focus in the atria takes over.

In PAT, these episodes may elicit a series of distinct heart rate increases, often described as "steps," due to the way the automaticity of the ectopic site progresses. This contrasts with other arrhythmias, which typically demonstrate either a more erratic rhythm or a sudden onset of high heart rates without such incremental changes.

Understanding the nature of the heart rate changes in paroxysmal atrial tachycardia is crucial for diagnosis and management, especially in differentiating it from other types of arrhythmias that do not present with this gradual escalation in heart rate.