Artificial intelligence can accurately predict how likely someone is to die within a year by looking at heart test results - even when doctors believe the person is healthy, The Daily Mail reported.

In a mystery diagnoses the machines are able to detect abnormalities in electrocardiogram (ECG) results and predict who is at higher risk of dying.

The artificial intelligence was given 1.77 million ECG results from 400,000 people to examine by Dr Brandon Fornwalt at healthcare provider Geisinger in Pennsylvania, US.

Two tests were carried out with one machine taught to only examine the raw data from the ECGs while the other was fed information about the people it related to - their sex, age.

To measure the AI's performance they tested its ability to distinguish between two groups of people - those who had died within a year of taking the tests and those who survived.

Miraculously when asked to predict which people were more at risk of dying within the next year the machines guessed very accurately.

When one is a perfect score matching every ECG with the correct outcome, the machine looking at the raw data alone scored eight point five, achieving a clear distinction between the groups - five is no distinction at all.

Surprisingly the machine that had been given additional information such as the patients sex and age did not do as well.

While still achieving between six and eight it seemed the machine was less able to measure the likelihood that the patients would die, when basing its predictions on information that doctors already use - such as age and sex.

Dr Fornwalt told the New Scientist: 'No matter what, the voltage-based model was always better than any model you could build out of things that we already measure from an ECG.'

The machine was able to detect abnormalities in ECGs that three trained cardiologists had determined were normal and nothing to worry about.