The research shows that boys with shorter ring fingers tend to be at greatest risk.

This is because these boys tend to have lower levels of the male sex hormone testosterone, which is known to protect against heart attack.

The genes that are indirectly responsible for the production of testosterone and the female hormone oestrogen also control the development of the fingers.

Relatively long

Lead researcher Dr John Manning stated "Males tend to have a relatively longer ring finger compared to the index finger than females.

"This is a very early trait and it is under the influence of sex hormones.

"For a man, the ring finger tends to be about 2% longer than the index finger. The longer your ring finger, the more protected you are against heart attack, because the more testosterone you have.

"There is a relationship between the ratio between these two finger lengths and the age at heart attack of people who do have heart attacks."

The ratio between the two fingers remains the same throughout life.

Short ring fingers did not necessarily mean that boys would go on to have heart attacks, but should alert their parents to do what they can to lessen the risk.

Dr Manning said: "This is an indicator of risk independent of things like smoking and diet, so you can adjust your diet and stop smoking and so on, if you are in a high-risk group."

Dr Manning and Dr Peter Bundred examined 151 male heart attack victims in Merseyside.

They found the age range for heart attacks in men where the index finger was relatively long was 35 to 80 years of age, but in those with relatively long ring fingers it was 58 to 80.

Dr Manning has previously uncovered links between finger-length and vulnerability to depression and sporting ability.

The research is to be published in the British Journal of Cardiology.