Cardiac arrest, also known as sudden cardiac arrest, is when the heart suddenly and unexpectedly stops beating.[11][1] As a result, blood cannot properly circulate around the body and there is diminished blood flow to the brain and other organs. When the brain does not receive enough blood, this can cause a person to lose consciousness. Coma and persistent vegetative state may result from cardiac arrest. Cardiac arrest is also identified by a lack of central pulses and abnormal or absent breathing.[1]

Reference
Wiki: Sudden cardiac failure