CARDIAC arrests are one of the deadliest medical emergencies you can suffer.
They occur when your heart stops beating and affect around 30,000 Brits a year outside of hospital, killing more than 90 per cent.
Cardiac arrests are different to heart attacks — where the blood supply to the organ is cut off.
They are caused by abnormal heart rhythms when the body's electrical system isn’t working properly.
A person will die within minutes unless they are treated immediately with CPR.
However, there are some signs you can spot before an arrest occurs.
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Dr Kyndaron Reinier, of the Cedars-Sinai Health System in Los Angeles, said: “Warning symptoms hold promise for predicting an imminent sudden cardiac arrest.”
Around half of patients have symptoms in “the hours, days, or weeks before their cardiac arrest”, she said.
Her study, published in the Lancet, looked at how common symptoms were in cardiac arrest patients and a control group of non-cardiac arrest patients who also called emergency services.
Researchers studied more than 1,500 adults in the US to see if any could indicate an attack was about to happen.
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Shortness of breath
The most common early sign of a cardiac arrest was shortness of breath — known medically as dyspnoea.
Some 41 per cent of patients suffered the sign, compared to 22 per cent in the control group.
It was the only sign to be significantly linked to cardiac arrests in both men and women, researchers said.
Chest pain
Chest pain was the second most common sign.
It affected around a third of patients, compared to a quarter of the control group.
However, it was only significantly linked to cardiac arrests in men — not women.
Sweating
Diaphoresis — or heavy sweating — also affected more cardiac arrest patients than others in emergencies.
Around 12 per cent had the symptom, compared to eight per cent in the control group.
It was also only significantly linked in men, not women.
Seizures
Finally, “seizure-like activity” was also more common in cardiac patients than the control group.
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Eleven per cent had the symptom, compared to seven per cent.
Nausea or vomiting, weakness, dizziness, and abdominal symptoms were all more common in the control group.