Most cases of sudden cardiac arrest occur outside of hospital and less than one in 10 of these will survive. However new research indicates that in many cases, there are warning signs before the event.

Cardiac arrest refers to the sudden loss of function of the heart. It occurs when there is an abrupt disturbance in the heart's rhythm. This can cause the heart to stop beating.

A person whose heart has stopped beating will fall unconscious and stop breathing normally. If they do not get immediate medical assistance, sudden cardiac death will follow. An estimated 5,000-6,000 deaths in Ireland every year are due to cardiac arrest.

US researchers analysed data from an 11-year study on unexpected death, which involved one million people. They focused specifically on the health history and symptoms of men aged between 35 and 64, who had suffered a cardiac arrest outside of hospital between 2002 and 2012.

The researchers found that among 567 men who suffered cardiac arrests outside of hospital, over half (53%) had symptoms prior to the event. Among those with symptoms, 56% had experienced chest pain, 13% had shortness of breath and 4% had palpitations, dizziness or fainting.

In four out of five of these cases, the symptoms occurred between one hour and four weeks before the cardiac arrest.

"The lesson is, if you have these kinds of symptoms, please don't blow them off. Go see your healthcare provider. Don't waste time," commented lead researcher, Dr Sumeet Chugh, of the Cedars-Sinai Heart Institute.

Details of these findings were presented at the American Heart Association's Scientific Sessions 2013.