About 225,000 sudden cardiac deaths occur each year among U.S. adults. All known heart diseases can lead to sudden cardiac death. Some are due to extreme slowing of the heart. All these events are called life-threatening arrhythmias . While a heart attack may cause cardiac arrest and sudden cardiac death, the terms aren't synonymous.
Cardiac arrest is reversible in most victims if it's treated within a few minutes.
This first became clear in the early 1960s with the development of coronary care units. Electrical devices that shocked the heart were used to turn an abnormally rapid rhythm into a normal one. In-hospital survival after cardiac arrest in heart attack patients improved dramatically when the DC defibrillator and bedside monitoring were developed. Later, it also became clear that cardiac arrest could be reversed outside a hospital by properly staffed emergency rescue teams trained to give CPR and defibrillate. Thus, the problem isn't the ability to reverse cardiac arrest, but reaching the victim in time to do so.