Although SCA is sometimes unpredictable, there are certain factors that may place you more at risk, including:
If you have any of these risk factors, talk with your doctor about having a cardiac evaluation, including a visit to an electrophysiologist (EP), a doctor with special training in diagnosing and treating irregular heart rhythms caused by improper electrical functioning of the heart. Therapies are available that can markedly reduce the risk in many individuals, including implantable cardioverter defibrillators (ICDs).
It's important to remember than although pre-existing heart disease is a common cause of cardiac arrest, many victims have no known heart problems. Fifty percent of men and 63 percent of women who experience arrest due to coronary heart disease (blockage of blood vessels) have no prior symptoms.  The chances of experiencing SCA do increase with age, with average age of occurrence being 60 years. 
 American Heart Association: National Heart, Blood and Lung Institute data. Framingham Heart Study.  American Heart Association Web site, January 2011.
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