Leech saliva drug could cut heart attacks by a third

By Celia Hall, Medical Editor
Last Updated: 9:55PM BST 02 Sep 2001

A DRUG derived from the saliva of leeches can reduce the risk of a repeat heart attack by a third, according to the results of an international study released yesterday.

Two centuries after the medical leech had its heyday in Western medicine, blood-thinning properties of the leech's saliva have been found to be more effective than another drug commonly used for heart attack patients.

Bivalirudin, a new, genetically engineered form of hirudin, the substance in the leech's saliva that stops blood clotting, was used in an international trial involving 17,000 patients, including 225 patients from Nottingham. It was compared with heparin, another blood-thinning agent.

Prof Harvey White, of Green Lane Hospital, Aukland, New Zealand, who led the study, told a briefing at the European Society of Cardiology meeting in Stockholm yesterday that the results confirmed the effectiveness of a new range of heart drugs.

Heart attacks are caused when a blood clot blocks the supply of blood to the heart. Untreated, the heart muscle is starved of oxygen and muscle cells begin to die. Heart attack patients are now routinely treated with a blood-thinning drug - in Britain this is usually aspirin - and clot-dissolving drugs.

About one patient in every 20 who has a heart attack has another shortly afterwards. Researchers are constantly seeking better drugs to stop repeat attacks which weaken the heart further, risk death and reduce the chances of a good recovery.

Prof White said they had found that bivalirudin was 30 per cent more effective than heparin in preventing a repeat attack. For every 1,000 patients treated with bivalirudin within 30 days of their heart attack, eight fewer subsequent heart attacks were recorded than among those treated with heparin.

Prof Sir Charles George, of the British Heart Foundation, said yesterday that studies had increasingly shown that combined therapy after a heart attack was better than a single drug in preventing another attack.

Dr Eric Topol, chairman of cardiovascular medicine at the Cleveland Clinic, Ohio, said: "The results of this trial are momentous. This is an important drug in the treatment of heart attacks."

Leeches were widely used in the 19th century to let blood, though belief in their ability to purge unhealthy "humours" goes back to medieval medicine.

During blood letting, dozens of leeches were sometimes applied to a patient resulting in blood loss of up to 80 per cent. More recently leeches have been used to drain blood from bruising and inflammation. They are also sometimes used in plastic surgery.