Why der is RP more than PR in atrial tachycardia?

Why der is RP more than PR in atrial tachycardia?

Atrial tachycardia (AT) is a type of abnormal heart rhythm , or arrhythmia.

It occurs when the electrical signal that controls the heartbeat starts from an unusual location in the upper chambers (atria) and rapidly repeats, causing the atria to beat too quickly.