Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the symptoms of Sudden Cardiac Arrest ?
    ### Response:
    Usually, the first sign of sudden cardiac arrest (SCA) is loss of consciousness (fainting). At the same time, no heartbeat (or pulse) can be felt.
                
Some people may have a racing heartbeat or feel dizzy or light-headed just before they faint.
    