Cardiac arrest is the loss of heart function, breathing and consciousness. It results from an electrical disturbance in your heart that disrupts its pumping action, stopping blood flow to the rest of your body. It is often sudden and unexpected and occurs with no warning. Symptoms are immediate and drastic and include: sudden collapse, no pulse, no breathing, loss of consciousness. Sometimes other signs and symptoms precede cardiac arrest. These may include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting.
Sudden Cardiac Arrest, Mayo Clinic (Mar. 7, 2018), https://www.mayoclinic.org/diseases-conditions/sudden-cardiac-arrest/symptoms-causes/syc-20350634