Leech offer lifeline for heart patients

Green Lane Hospital researchers achieve a breakthrough with a drug derived from leeches' saliva, writes SHENAGH GLEESON.

A substance found in the saliva of leeches offers new hope for heart patients.

New Zealand researchers have led the world's biggest clinical trial to establish that a drug derived from hirudin, the substance in leeches' saliva that stops bloodclotting, can reduce the risk of repeat heart attack by nearly a third.

The results of the trial of bivalirudin have been hailed as momentous, proving that the new drug offers a significant improvement in the treatment of heart disease.

Heart attacks are caused when a bloodclot blocks the supply of blood to the heart. Untreated, the heart muscle is starved of oxygen and muscle cells start to die.

Patients are treated with a blood-thinning drug and a clot-dissolving drug.

About one patient in 20 who has a heart attack has another one shortly afterwards and 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.

Professor Harvey White, director of coronary care and cardiovascular research at Green Lane Hospital, led the trial of bivalirudin and a team of 20 researchers.

Back at work in Auckland yesterday after releasing the trial results at a meeting of the European Society of Cardiology in Stockholm, he said he was proud of what Green Lane researchers had achieved. "This shows we can take on the world."

Leeches, widely used in the 19th century to suck blood, are used in New Zealand in plastic and reconstructive surgery to anaesthetise wound areas, dilate blood vessels to increase bloodflow, and prevent the blood from clotting.

Hirudin was identified in 1996 and genetically engineered to produce bivalirudin.

A year later Dr Harvey and his team at Green Lane Hospital began trials of Angiomax, a bivalirudin drug, developed by the Medicines Company in the United States.

After an initial trial of 400 patients to work out the dose, the Green Lane team launched the HERO-2 trial, involving 17,000 patients in 46 countries, to compare bivalirudin and heparin, another blood-thinning agent. Patients were also given the clot-buster streptokinase and aspirin.

The three-year trial found that bivalirudin was 30 per cent more effective than heparin in preventing repeat attacks.

Among every 1000 patients treated with the new drug within 30 days of their heart attack, eight fewer subsequent heart attacks were recorded than among those treated with heparin.

"This is an important finding, signalling a change in clinical practice," Professor White said.

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

"The finding of substantial reductions in repeat heart attacks is a significant step forward in patient care."

Professor White said that bivalirudin was available in New Zealand and approval for its use in heart attacks would be sought.

The Green Lane team also plans to look into the higher death rate of women in the study.