Final answer:
Atrial fibrillation does not routinely require the start of CPR, unlike ventricular fibrillation, which is an emergency situation requiring immediate intervention including CPR and defibrillation.
Step-by-step explanation:
Atrial fibrillation is not routinely a reason to begin CPR (cardiopulmonary resuscitation). The condition, while serious, does not typically pose an immediate threat to life as long as the ventricles continue to pump blood. In contrast, ventricular fibrillation is a life-threatening emergency that does require immediate intervention, such as CPR and defibrillation, because the ventricles are not effectively pumping blood. The primary treatment for ventricular fibrillation is defibrillation, which applies a charge to the heart with special paddles or an automated external defibrillator (AED) to establish a normal sinus rhythm, often preceded by CPR if the patient is unresponsive and not breathing normally.