Final answer:
The most important dysrhythmia to apply and engage an automatic external defibrillator (AED) is Ventricular fibrillation.
Step-by-step explanation:
The most important dysrhythmia to apply and engage an automatic external defibrillator (AED) would be Ventricular fibrillation. Ventricular fibrillation is a medical emergency where the ventricles are not effectively pumping blood, and if untreated, it can lead to brain death in just a few minutes. AEDs are effective in reestablishing a normal sinus rhythm and can be used by nonmedical personnel to save a person's life.