London, Nov 30 (IANS): If you are under the age of 50 and a regular smoker, you may be more than eight times at risk of suffering a major heart attack as compared to non-smokers or people who quit smoking, researchers have warned.

The study showed that smokers of all age-group were more than three times likely to have a STEMI than ex- and non-smokers combined.

But the highest risk was among the under-50s who were nearly 8.5 times as likely to do so as former and non-smokers of the same age.

According to researchers, this risk, however, fell with increasing age, dropping to a five-fold difference among 50-65 year olds, and a three-fold difference among the over 65s.

A STEMI, or ST-segment elevation myocardial infarction, refers to the typical pattern seen on an electrocardiogram (ECG), indicating that a large portion of the heart muscle is dying.

In the study, current smokers tended to be 10-11 years younger than ex- or non-smokers when they had their STEMI. And, along with ex-smokers, were twice as likely to have had previous episodes of coronary artery disease.

They were also three times likely to have peripheral vascular disease -- a condition in which a build-up of fatty deposits in the blood vessels restricts blood supply to the legs, the researchers said.

"All current smokers must be encouraged into smoking cessation therapy to reduce their risk of acute STEMI, with a focus on the youngest smokers whose increased risk is often unrecognised," said Ever D Grech from the Northern General Hospital in Britain.

For the study, published online in the journal Heart, the team drew on data for 1,727 adults among which almost half (48.5 per cent) were current smokers, with roughly a quarter (just over 27 per cent) former smokers, and a quarter (just over 24 per cent) non-smokers.