A major international trial has been set up to see whether a treatment to increase so-called "good" cholesterol can prevent heart attacks and strokes.

"Good" cholesterol - high density lipoproteins (HDL) - cuts heart disease risk removing fat from the circulation.

The treatment, designed to increase levels of HDL, will be given alongside drugs to reduce "bad" cholesterol, which can raise the risk of disease.

A team at Oxford University is leading the trial involving 20,000 volunteers.

To be eligible for the trial patients must be aged between 50 and 80 with a history of heart attack, stroke or peripheral artery disease.

Around 7,500 men and women will be recruited from the UK with people from China and Scandinavia making up the rest of the participants.

The main ingredient in the trial drug is niacin, which has been found to increase levels of HDL by between a fifth and a quarter as well as decreasing dangerous fatty substances called triglycerides.

But patients have found it difficult to take niacin long-term because it produces an uncomfortable side-effect of flushing.

To combat this effect, niacin has been combined with another drug, which blocks the release of prostaglandin D2 - the substance which produces the flushing effect.

The team at the Clinical Trials Unit at Oxford previously carried out the landmark Heart Protection Study which showed a third of all heart attacks and strokes could be avoided in people at risk of vascular disease by using statins to lower "bad" cholesterol or low density lipoproteins (LDL).

Large-scale trials have shown that lowering LDL for four to five years cuts the risk of heart attacks and stroke by a quarter.

But the risk among patients who already have vascular disease remains high even with the use of statins and there is limited scope for reducing LDL much more so researchers are starting to look at ways of also increasing HDL.

'The next step'

Dr Jane Armitage who is leading the trial said: "The difficulty has been that there haven't been good quality drugs that raise HDL very much.

"The trial will be in people at risk of future heart problems despite the fact that their LDL cholesterol has been lowered.

"If it's shown to work the epidemiology suggests it will be possible for people at lower risk of heart problems to benefit," she said.

Professor Gilbert Thompson, a lipidology expert at Imperial College said treatments which raise HDL were the "next step" in cholesterol research.

"It seems a perfectly reasonable approach but it won't necessarily give you a straight answer about HDL because niacin also lowers triglyceride. But it will be a good trial.

Dr Anthony Wierzbicki, Chair of Heart UK Scientific Medical and Research Committee, said looking for ways of raising HDL in addition to lowering LDL was the next logical step.

"There are a number of trials looking at this that are either under way or starting soon all following the protocol of adding HDL-raising agents to baseline statin therapy in a variety of patient populations."

A group of drugs called CETP inhibitors have also been shown to increase levels of "good" cholesterol and are currently in clinical trials.

http://news.bbc.co.uk/1/hi/health/5029616.stm