A London hospital wants to introduce random urine testing of patients arriving with chest pain - to test for cocaine use.

The drug is well-known for causing heart problems, and staff at St Mary's Hospital want to find out how many people coming to casualty with these symptoms have been taking it.

Professor John Henry, a consultant in toxicology at St Mary's said the testing could be done anonymously for the purposes of research, and would not prejudice the treatment of any patient.

He is seeking hospital approval as to whether the tests would be ethical.

He said: "We have looked at 100 sets of records of people who come in with chest pains, and we found three of them volunteered the fact that they had taken cocaine.

"If we did some sort of testing or even questioned them more closely, we would find the number was a lot more than that."

While doctors can perform a variety of tests on an unconscious person without his or her consent if they feel they could help determine the source of the problem, a conscious patient in casualty would have to give permission for urine samples to be taken, and the tests could not be made a pre-condition of treatment.

Professor Henry described it as a "relatively small problem", but with cocaine use accelerating in some sections of society, warned that younger people were running a high risk of heart disease.

Violent artery spasm

He said: "It will lead to premature aging, and furring of the arteries. When the message gets through that you are really running a risk, then people will think twice."

The initial effect of cocaine is a violent constriction of arteries - including those supplying the heart muscle, which can produce the chest pain symptom.

Normally, in an otherwise fit, young person, the symptoms will settle down, but occasionally a full heart attack will be triggered.

Long-term use of the drug can cause problems because of the repeated stresses involved.

A report in New Scientist this week said that cocaine actually encouraged the body's own immune system to attack healthy cardiac muscle tissue.

The study, based at the University of Michigan, found that the drug boosted the formation of certain proteins in the hearts of rabbits, causing cells to burst.