Sudden Cardiac Arrest

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Learn about sudden cardiac arrest and what the HeartSafe Program is doing to overcome it.

Definition
Causes
Signs and Symptoms
Diagnoses
Risk Factors
Additional Risk Factors
Sudden Cardiac Key Facts
Sudden Cardiac Arrest Statistics

Definition

Sudden cardiac arrest is a sudden electrical disturbance in the heart that interrupts the heart’s pumping action and stops the normal circulation of blood to the brain and other vital organs. The lack of oxygen to the brain results in loss of consciousness, breathing, and pulse and causes the victim to suddenly collapse.

Sudden cardiac arrest is not the same as a heart attack. A heart attack occurs when blood flow to a portion of the heart is blocked, depriving the heart muscle of necessary oxygen. Similar to a heart attack, however, sudden cardiac arrest often occurs as a result of an underlying heart condition.

Sudden cardiac arrest is a medical emergency. It is fatal, if not treated immediately. With fast, appropriate medical care, survival is possible. Administering cardiopulmonary resuscitation (CPR) and using an automated external defibrillator (AED) can improve a victim’s chance of survival by up to 75 percent.

People with heart disease have a higher chance of having SCA. But most SCAs happen in people who appear healthy and have no known heart disease or other risk factors for SCA.

Causes

Most cases of sudden cardiac arrest (SCA) are due to an arrhythmia called ventricular fibrillation (v-fib). In v-fib, the ventricles (the large pumping chambers of the heart) quiver very rapidly and irregularly instead of beating normally. When this happens, the heart pumps little or no blood to the body.

Other electrical problems that can cause SCA are extreme slowing of the rate of the heart’s electrical signals or when heart muscle stops responding to the electrical signals.

Several factors can cause the electrical problems that lead to SCA. These factors include:

  • Severe physical stress
  • Inherited disorders
  • Coronary artery disease
  • Structural changes in the heart

Signs and Symptoms

Usually, the first sign of sudden cardiac arrest is loss of consciousness, which is similar to fainting. At the same time, breathing often stops and no heartbeat (or pulse) can be felt. Some people may first notice that they have a racing heartbeat or feel dizzy or lightheaded just before they faint.

Diagnoses

Sudden cardiac arrest (SCA) happens without warning and requires immediate treatment. Rarely is there a chance to diagnose it with medical tests as it is happening. Instead, SCA is often diagnosed after it happens, by ruling out other causes of the patient’s sudden collapse. Click here to see a description of Diagnostic Tests and Procedures.

Risk factors

The most important risk factor for SCA is having coronary artery disease (CAD). Many people with SCA had a silent heart attack before the SCA happened. These people have no obvious signs of having a heart attack, and they don’t even realize that they’ve had one. The chances for having SCA are higher during the first 6 months after a heart attack.

Additional Risk Factors

  • A personal or family history of SCA
  • Abnormal heart rhythms (arrhythmias)
  • Birth defects of the heart or blood vessels, or an enlarged heart
  • Heart failure
  • Recreational drug abuse

Sudden Cardiac Arrest Key Facts

  • Sudden Cardiac Arrest (SCA) is a leading cause of death in the United States, accounting for an estimated 325,000 deaths each year
  • In SCA, the heart abruptly and unexpectedly ceases to function (cardiac arrest). It is an “electrical problem” caused by a heart rhythm disorder called Ventricular Fibrillation (VF). In SCA, the heart is no longer able to pump blood to the rest of the body.
  • SCA is NOT a heart attack – a condition technically known as a myocardial infarction (MI). MI is a “plumbing problem” in which a blockage in a blood vessel interrupts the flow of blood to the heart causing an “infarct” – an area of dead heart muscle. SCA may, however, occur in association with a heart attack.
  • VF occurs when the electrical signals that control the pumping ability (contractions) of the lower chambers of the heart (ventricles) suddenly become rapid and chaotic. The ventricles begin to quiver and can not longer pump blood from the heart to the rest of the body.
  • SCA is NOT a random event. Although it may occur in outwardly healthy people, most victims DO have heart disease or other health problems, often without being aware of it.
  • Without emergency help, SCA leads to death within minutes.
  • Victims of cardiac arrest can be saved if a defibrillator device is immediately available to deliver an electric shock to restore the heart to its normal rhythm.
  • The chain of survival for victims of SCA has 4 links:

If the chain of survival were properly implemented in our communities, more than 68,000 additional lives could be saved each year.

  • People who are at high risk for SCA may be treated with implantable cardioverter defibrillators (ICDs), devices that are implanted under the skin. ICDs monitor the heart’s rhythm and automatically deliver a short, high-energy shock when the individual develops an irregular heart rhythm that may lead to SCA.
  • Studies have shown that ICDs are the best way to prevent cardiac arrest in certain groups of patients who are at high risk.

Sudden Cardiac Arrest Statistics

  • Sudden Cardiac Arrest (SCA) is a leading cause of death in the United States, claiming an estimated 325,000 lives each year.
  • SCA kills 1,000 people a day or one person every two minutes.
  • SCA most often occurs in patients with heart disease, especially those who have congestive heart failure and have had a heart attack.1
  • It is estimated that 95 percent of victims of cardiac arrest die before they reach a hospital or other source of emergency help.
  • As many as 75 percent of people who die of SCA show signs of a previous heart attack. Eighty percent have signs of coronary artery disease.
  • SCAs accounted for 10,460 (75.4 percent) of all 13,873 cardiac disease deaths in persons aged 35-44 years, and the proportion of cardiac arrests that occurred out-of-hospital increased with age, from 5.8 percent in persons aged 0-4 years to 61.0 percent in persons aged >85 years.2
  • SCAs accounted for 63.7 percent of all cardiac arrests among whites, 62.3 percent among African Americans, 59.8 percent among American Indians/Alaska Natives, 55.8 percent among Asians/Pacific Islanders, and 54.2 percent among Hispanics. Whites had the highest proportion of cardiac arrests out-of-hospital, and African Americans had the highest proportion of cardiac arrests in an Emergency Department or dead on arrival. 3
  • According to the Centers for Disease Control and Prevention (CDC), deaths from sudden cardiac arrest increased 10 percent (from 2,719 in 1989 to 3,000 in 1996) in people between the ages of 15 and 34. In young women, the death rate from SCA increased 30 percent. African Americans are more likely to die from SCA than whites.
  • Wisconsin, Idaho, and Utah have the highest percentage of cardiac arrests. 4

1- AHRQ Research Activities, December 2002: Researchers examine the risk factors for sudden cardiac arrest and management of at-risk patients.
2 – MMWR Weekly February 15, 2002/51(06); 123-6: State-Specific Mortality from Sudden Cardiac Arrest — United States, 1999.
3 – MMWR Weekly February 15, 2002/51(06); 123-6: State-Specific Mortality from Sudden Cardiac Arrest — United States, 1999.
4 – MMWR Weekly February 15, 2002/51(06); 123-6: State-Specific Mortality from Sudden Cardiac Arrest — United States, 1999.