You can’t choose when Sudden Cardiac Arrest will strike. But You Can Be Prepared. Sudden Cardiac Arrest can happen to anyone, anywhere, at any time. When it happens, a HeartSine Automated External Defibrillator (AED) can make the difference between life and death. An AED can be used by untrained bystanders to increase the survival rate for SCA up to 75% by delivering a life-saving shock within the first few minutes of an attack.