Sudden cardiac arrest occurs when your heart beats so fast that it quivers instead of beating in a very regular and organized way. When the heart beats so fast, very little or no blood is pumped into the body and brain. If untreated, it may lead to death in minutes. SCA is not similar to an heart attack or infarction, because a defibrillator can restore the heart rate to normal. Defibrillators can be external, like those carried by emergency crews, or implanted in your body for long-term protection.