About Sudden Cardiac Arrest

Sudden cardiac arrest occurs when your heart beats so fast it quivers instead of pumping blood to the body and brain. Untreated, it can lead to death in minutes. If you are at risk, an implantable defibrillator can treat dangerously fast heart rhythms and provide ongoing protection against sudden cardiac death.


Sudden cardiac arrest occurs when your heart suddenly starts beating very fast and quivering, instead of pumping blood to the body and brain. If untreated, sudden cardiac arrest can lead to death in minutes.


Sudden cardiac arrest is caused by an electrical problem in the heart. This occurs when the heart starts beating dangerously fast causing it to quiver rather than pump blood to the body and brain.


Some people may experience a racing heart beat or feel dizzy, alerting them of a potentially dangerous heart rhythm. Others who experience sudden cardiac arrest may lose consciousness before they can ask for help.

Risk Factors

People at a higher risk for sudden cardiac arrest include those:

  • Who have had a heart attack (myocardial infarction)
  • Who have experienced heart failure (poor pumping heart)
  • Who have survived a previous sudden cardiac arrest
  • With a family history of sudden cardiac arrest
  • With a low ejection fraction

Ejection fraction, or the percentage of blood that is pumped out of the heart during each beat, is a key indicator of a healthy heart. Ejection fraction is frequently monitored by doctors to determine how well your heart is functioning as a pump.


Only your doctor can tell if you are at risk for sudden cardiac arrest. To evaluate your risk, your doctor may order one or more of these diagnostic tests:

  • Echocardiogram
  • Electrocardiogram (ECG)
  • Chest x-ray
  • Exercise test (stress test)
  • Cardiac catheterization

Information on this site should not be used as a substitute for talking with your doctor. Always talk with your doctor about diagnosis and treatment information.

Last updated: 27 Sep 2010

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