Oversensing can lead to a dangerous situation. If the threshold is set too low, other electrical components in the patient’s physiology may be detected and interpreted as an impulse coming from the heart. Impulses from the thoracic skeletal muscles, such as the pectoralis major and sternocleidomastoid muscles, may be detected and misinterpreted. This can lead to inhibition of the pacemaker that can persist for several heart cycles. Syncope may occur in patients who are dependent on the pacemaker.

Oversensing produces multiple small spikes on ECG during motion. These spikes are produced by the muscles. Pacemaker spikes are absent, which may lead ventricular asystole in certain patients. Oversensing may predominate during strenuous exercise, especially in younger individuals. Hence, they are restricted from strenuous activities that involve the upper extremities.