Heart disease is the number 1 killer in the United States. In 2020 (the most recent date for which there are statistics), one in every six deaths in the U.S. were caused by heart disease, according to the Centers for Disease Control.
Many of these deaths occur with little or no warning from a syndrome called sudden cardiac arrest. The most common cause of sudden cardiac arrest is a disturbance in the heart rhythm called ventricular fibrillation.
Ventricular fibrillation is dangerous because the heart doesn't pump blood, which cuts off blood supply to the brain and other vital organs. It often, though, can be treated successfully by applying an electric shock to the chest with a procedure called defibrillation.
In coronary care units, most people who experience ventricular fibrillation survive, because defibrillation is performed almost immediately. The situation is just the opposite when cardiac arrest occurs outside a hospital setting. Unless defibrillation can be performed within the first few minutes after the onset of ventricular fibrillation, the chances for reviving the person (resuscitation) are very poor.
For every minute that a person remains in ventricular fibrillation and defibrillation is not provided, the chances of surviving drop by almost 10%. After 10 minutes, the chances of reviving someone with cardiac arrest are near zero.
Cardiopulmonary resuscitation, usually known as CPR, provides temporary artificial breathing and circulation. It can deliver a limited amount of blood and oxygen to the brain until a defibrillator becomes available. However, defibrillation is the only effective way to resuscitate someone with ventricular fibrillation.