Heart drugs which save thousands of lives every year in the UK have been attacked by a scientist - who says they may actually cause heart failure.

Statins work by reducing the level of cholesterol in the blood of patients with heart disease.

Studies involving many thousands of patients have proved that taking them greatly reduces the chance of heart attacks and strokes.

Experts say that an increase in deaths from heart failure may well be a consequence of their success in keeping people with weakened hearts alive for many more years.

The new study from the US - to be presented at a scientific conference in London this week - suggests that taking statins may deplete the body's supplies of another chemical which helps keep the heart healthy.

I think people taking statins should be very worried

Dr Peter Langsjoen, East Texas Medical Center

Coenzyme Q10, say the study's authors is needed to prevent heart failure.

Dr Peter Langsjoen, from East Texas Medical Center, who carried out the research, said: "I think people taking statins should be very worried. I don't think this can be ignored."

However, his views have been challenged by UK experts, who say that the safety of statins has been extensively checked.

Claims challenged

Dr Tim Bowker, Associate Medical Director at the British Heart Foundation said:

"This new information should not change current practice on statin prescription.

What we do know, as a result of several large clinical trials, is that for people with heart disease the benefits of taking statins far outweigh the risks - they are living longer and are less likely to have repeat heart attacks."

For people with heart disease the benefits of taking statins far outweigh the risks

Dr Tim Bowker, British Heart Foundation

Dr Lansjoen said that the US - where statins have been available for much longer - there was an "epidemic" of heart disease, although doctors had not attributed these deaths to the long-term effect of statins.

"Most doctors have assumed these drugs are so safe that they don't attribute heart failure to the fact that people are taking them.

"Millions of men and women may be endangered," he said.

In the UK, the number of people living with heart failure has increased by 15% in recent years.

Experts have blamed the rise on the fact that modern surgery and drugs have prevented many thousands from dying as a result of heart attacks and strokes.

These people may well still have weakened hearts, making heart failure more likely.