A cheap and simple method of predicting who might be at risk of a sudden and unexpected heart attack in later life has been discovered by French scientists in Paris.

The team, working at the Hôpital Européen Georges Pompidou, found that people whose heart rate increased the most when faced with the prospect of taking exercise – something the researchers described as “mild mental stress” – had twice the risk of dying from a sudden heart attack in later years as individuals whose heart rate did not increase to the same extent.