Scientists have developed a quick, cheap blood test to predict a patient's chance of surviving a heart attack.

The test works by measuring levels of a hormone which is produced in greater quantity when the heart is damaged.

It outperformed other tests that are currently available, and proved to be accurate even in patients who showed no obvious clinical signs of being at risk.

Patients will be more willing to accept minor side effects if they know they are at heightened risk

Professor Martin Cowie

The outlook for patients who have had a heart attack or other cardiovascular problems such as angina varies widely.

Identification of those people at high risk is vital, as they may need surgery to try to minimise the likelihood of further problems.

High levels of the hormone B-type natriuretic peptide (BNP) are secreted by heart tissue when the heart is overloaded.

BNP is a diuretic, which helps to relieve pressure on the heart by stimulating the body to get rid of excess fluid through urination.

The new test focuses on a fragment of the hormone, called N-BNP.

Test results

The researchers, from Sahlgrenska University Hospital in G�thenburg, Sweden, followed the progress of 609 patients with heart problems over a six year period.

They found N-BNP levels were on average three times higher in patients who died during the period of the study than in those who survived.

People with the highest N-BNP levels were twice as likely to have died than those with the lowest levels.

Professor Martin Cowie, an expert in cardiology at Imperial College, London, told BBC News Online that heart patients were not always given the full range of treatments available to them because of the potential for side effects.

He said: "Patients might not want to take four or five tablets every day, and a test which can provide more information about those who are most likely to benefit may provide those patients with the extra motivation to take all the tablets that their doctor wants to give them.

"Patients will be more willing to accept minor side effects if they know they are at heightened risk."

Other tests

Current tests to determine a patient's long term risk include assessing their cardiac performance while exercising, and the use of an ultrasound device called an echocardiogram to measure heart function.

Belinda Liden, of the British Heart Foundation, said an effective way to identify heart patients at risk of further attacks would be most welcome.

She said: "It is already well researched that measuring the hormone BNP can diagnose heart failure in people who have had a heart attack - and this study again highlights the potential for hormone testing.

"However, we would welcome further research as it is early days for N-BNP testing and more needs to be known before the benefits can be confirmed."

The research is published in Circulation: Journal of the American Heart Association.