Sudden cardiac death (SCD) is a sudden, unexpected death caused by loss of heart function (sudden cardiac arrest). It is a leading cause of ''natural deaths'' in the U.S., causing about 295,000 adults to die each year. SCD is responsible for half of all heart disease deaths.
SCD occurs most frequently in adults in their mid-30s to mid-40s, and affects men twice as often as it does women. SCD is rare in children, although the exact prevalence is not known.
Sudden cardiac arrest can be treated if addressed within the first few minutes. The American Heart Association promotes the following four steps, called "the chain of survival:"
Early Access to Care. Quick contact with emergency care is essential. Call 911 (in most communities) or your local emergency number immediately.
Early Cardiopulmonary Resuscitation (CPR). Learning CPR is the greatest gift you can give your family and friends. If performed properly (see below), CPR can help save a life until emergency medical help arrives.
Early Defibrillation. In most adults, sudden cardiac death is related to ventricular fibrillation. Quick defibrillation (delivery of an electrical shock) is necessary to return the heart rhythm to a normal heartbeat. Many public places, such as malls, golf courses, and airports, have automated external defibrillators (AEDs; see below) available for use in emergency situations.
Early Advanced Care. After successful defibrillation, most patients require hospital care to treat and prevent future events.
These four steps can increase survival as much as 90% if initiated within the first minutes after sudden cardiac arrest. Survival decreases by about 10% each minute longer.