Cardiac arrest is also called sudden cardiac death (SCD). Cardiac arrest is the largest cause of natural death in the U.S. resulting in 325,000 adult deaths per year. During cardiac arrest, the heart stops pumping blood around the body. A person promptly loses consciousness. If the pumping of the heart is not restored within 4 minutes, the brain will die. Starting CPR immediately is the number one determinant of a patient surviving a cardiac arrest.