Causes of wandering atrial pacemaker are unclear, but there may be factors leading to its development.

In wandering atrial pacemaker, there are other locations within the atria besides the SA node that are responsible for each heartbeat.

[3] Wandering atrial pacemaker may be seen in young, healthy individuals as well as in the elderly and those with lung disease.

Increased tone from the vagus nerve may factor into the rhythm appearing in young, healthy individuals who exercise.

In rare cases, digoxin toxicity can cause wandering atrial pacemaker.

It is usually found incidentally on an ECG for other medical indications that require a heart rhythm screening.

To make the diagnosis, there must be at least 3 different P-wave morphologies in a single ECG lead due to the shifting of the pacemaker in the atria.

[1] This is different from normal sinus rhythm where one will see the same P-wave morphology through the same lead because each beat is started from the SA node.