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Sudden Cardiac Arrest

Signs and Symptoms of Sudden Cardiac Arrest¹

The first and often only symptom of Sudden Cardiac Arrest is loss of consciousness (fainting) due to lack of blood to the brain. At the same time, no heartbeat or pulse can be felt.

While there are often no warning signs before Sudden Cardiac Arrest occurs, some of these symptoms may come before Sudden Cardiac Arrest:

  • Fatigue or weakness
  • Shortness of breath
  • Fainting
  • Dizziness or lightheadedness
  • Heart palpitations
  • Chest pain

Some people who are said to have died from a "massive heart attack" may instead have died from Sudden Cardiac Arrest.

Chances of Survival

The definitions of Sudden Cardiac Arrest and heart attack are completely different. A heart attack is a "plumbing" problem caused by one or more blockages in the heart's blood vessels that prevent proper flow. A person having a heart attack is awake and breathing.

The chances of surviving Sudden Cardiac Arrest decrease by 7-10% with every minute that passes without a life-saving shock.² The good news is that immediate treatment with cardiopulmonary resuscitation (CPR) and a defibrillator (a device that sends an electric shock to the heart) can be lifesaving. In fact, defibrillation has been shown to effectively stop 95% or more of dangerously fast heart rhythms.³

Defibrillation effective in stopping dangerously fast heart rhythms in 95% or more


1. CRM-255503-AA 2.4 Sx SCA final.doc/Page 3;
2. National Heart, Lung, and Blood Institute – What is Sudden Cardiac Arrest? Available at: Accessed June 7, 2014.
3. Himmrich E, et al. Is ICD programming for double intraoperative defibrillation threshold energy safe and effective during long-time follow-up? Results of a prospective randomized multicenter study (Low-Energy ENDOTAK Trial - LEFT). Z Kardiol. 1999;88:103-12 [German language edition].

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