“Most cardiac arrests occur when a diseased heart’s electrical system malfunctions. This malfunction causes an abnormal heart rhythm such as ventricular tachycardia or vent.”ricular fibrillation. Some cardiac arrests are also caused by extreme slowing of the heart’s rhythm (bradycardia).  There are other rhythms that can also cause cardiac arrest.”

American Heart Association (https://www.heart.org/en/health-topics/cardiac-arrest/causes-of-cardiac-arrest)