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Tuesday, 17 April, 2001, 00:27 GMT 01:27 UK
Heart disease cause pinpointed
Heart monitor
A form of cholesterol has been pinpointed
A specific form of cholesterol has been singled out as a cause of heart disease by scientists.

They say people with high levels are more likely to suffer from severe heart disease.

It is hoped the discovery could lead to a new test to diagnose patients who are most at risk.

Cholesterol has long been linked to heart disease, but Japanese researchers have pinpointed the main culprit as a form of cholesterol called low density lipoprotein (LDL) which has combined with oxygen.

Future studies could lead to the development of a test to find out who is most at risk from having a heart attack

British Heart Foundation
The scientists measured the levels of oxidised LDL in deposits which build up in the blood vessels called plaques.

These plaques are thought to play a major role in causing heart disease by clogging up the arteries - a process called atherosclerosis.

It was found that oxidised LDL was present at higher levels in the plaques of people with unstable angina than in those with the stable form of the condition.

Stable angina is chest pain that occurs during exertion. People with unstable angina experience chest pain even while at rest.

The researchers, from Osaka City University Medical School studied 135 patients who had various signs and symptoms of heart attack or angina.

There were 45 patients with heart attack, 45 patients with unstable angina, 45 patients with stable angina, and a control group who had no symptoms.

The patients with heart attack were studied within 24 hours of the onset of chest pain.

Blood samples were taken from all patients when they were admitted to the hospital, and analysed for levels of oxidised LDL in the plasma.

Researchers found that average levels of oxidised LDL in patients who had a heart attack were 64% higher than in patients with unstable angina, more than twice as high as in patients with stable angina and four times that found in the healthy controls.

In effect, the more serious the condition, the higher the oxidised LDL.

Cross sections

For the second part of the study, researchers analysed sections of coronary arteries from 10 patients with stable angina and 23 with unstable angina.

The sections were taken directly from the area believed to have caused the blockage responsible for the chest pain.

They found that oxidised LDL levels in the crucial area were on average seven times higher among those with unstable angina.

Dr Sotirios Tsimikasdicine, of the University of California at San Diego, said the research was unique because it looks at different groups of patients using the same LDL measurements.

He said: "The levels of oxidised LDL circulating in the blood correlate well with the severity of disease.

"The sicker the patient, the higher the levels of circulating oxidised LDL, indicating that it is a marker of atherosclerotic plaques."

A British Heart Foundation spokeswoman said: "There is already much evidence suggesting that cholesterol oxidises before it is deposited within the coronary artery lining, and this may accelerate the furring of the arteries that can lead to a heart attack.

"This oxidisation may be prevented to some extent with antioxidant nutrients found especially in fruit and vegetables.

"The diagnostic test described in this research cannot be applied outside the research laboratory to assess a patient's risk of having a heart attack - but future studies could lead to the development of a test to find out who is most at risk from having a heart attack."

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

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