London, May 31 (IANS): Challenging established medical practice that all heart attack patients should be on beta blockers, a new study claims that some such patients may not benefit from the medication.

The study looked at patients who had a heart attack but did not suffer heart failure -- a complication of a heart attack where the heart muscle is damaged and ceases to function properly.

It found that heart attack patients who did not have heart failure did not live any longer after being given beta blockers -- yet around 95 per cent of patients who fall into this category end up on the medication.

"If you look at the patients who had a heart attack but not heart failure -- there was no difference in survival rates between those who had been prescribed beta blockers and those that had not," said lead investigator Marlous Hall from University of Leeds in Britain.

Beta blockers are a powerful group of medicines which decrease the activity of the heart and lower blood pressure.

They are commonly prescribed after a heart attack, but they can have unwanted side-effects for some patients such as dizziness and tiredness.

Not all people who have their first heart attack have heart failure. Patients with a heart attack and heart failure need to be on beta blockers because the drugs help the damaged heart to work more effectively.

The University of Leeds investigation, though, focused on those patients with heart attack who did not have heart failure but were still prescribed beta blockers.

The study wanted to see if being on beta blockers made any difference to the chances of these patients being alive one year after their heart attack.

The research -- published in the Journal of the American College of Cardiology -- raises the possibility that the drugs are being over prescribed, and may burden patients with unnecessary medicine costs.

The research team analysed data from Britain's national heart attack register which collects information on people hospitalised following a heart attack.

They looked at data from more than 179,000 patients who had a heart attack without heart failure.

When investigators compared death rates within a year of the patients suffering a heart attack, they found no statistical difference between those who had been prescribed the drugs and those who had not.