A cardiac arrest occurs when the heart is knocked out of rhythm and suddenly stops beating. However, as so few patients survive the ordeal it has been difficult to pinpoint whether those affected experience similar symptoms.

However, researchers at the Cedars-Sinai Heart Institute in Los Angeles now believe that the warning signs exist, but are going unnoticed.

To make their findings for the Oregon Sudden Unexpected Death Study, the team assessed medical records from nearly 1,100 people aged between 35 and 65 who had suffered cardiac arrest. They also conducted interviews with witnesses of cardiac arrests, as well as the friends and families of patients. 

They found that around half of the middle-aged patients for whom information was available had reported experiencing chest pain or shortness of breath in the month prior to the cardiac arrest.

The symptom information for around a quarter of the patients was unavailable, however, evidence for the remaining 839 patients revealed that half had at least one symptom in the previous month.

Signs patients showed before experiencing cardiac arrest, according to the study

• Chest pain
• Shortness of breath
• Fainting
• Heart palpitations

Many experienced symptoms 24 hours before their collapse, while some noticed a difference in their condition between around a week and a few up to a month before.

Chest pain was most common in men, while women were more likely to experience shortness of breath. Other symptoms included fainting and heart palpitations.