Sudden Cardiac Arrest (SCA) can happen when the lower chambers (ventricles) of the heart beat very fast and irregularly, causing the heart to stop because it can't handle the pace. SCA is the leading cause of death in the United States, claiming more than 350,000 lives each year. Approximately 92% of those who experience SCA do not survive. Defibrillation using an Automated External Defibrilator (AED) or an Implanted Cardioverter Defibrillator (ICD) is the most effective treatment for Sudden Cardiac Arrest. SCA is not the same as a heart attack.