Cocaine goes straight to the heart

January 18, 2000

The fashion for cocaine may be causing a wave of heart disease among young people. Besides its known effect of sending coronary arteries into spasm, the drug also encourages the immune system to turn on healthy cardiac tissue, researchers in Michigan have discovered.

The work comes as some doctors are complaining that the abuse of the drug is causing a hidden drain on already stretched hospital resources. They believe that cocaine is making large numbers of otherwise fit young people-most of them men-report to emergency departments with chest pains.

The immunological study, led by Benedict Lucchesi of the University of Michigan in Ann Arbor, suggests that cocaine activates a part of our immune defences called the complement cascade. This system, which is usually triggered by invading microorganisms, destroys cells by building complexes of proteins on cell membranes, causing the cells to burst.

Working on rabbit hearts, the Michigan team has shown that cocaine boosts the production of complement proteins, causing the deadly complexes to form on heart muscle cells and the endothelial cells that line the heart's blood vessels.

The complement cascade is already known to damage heart tissue in some circumstances (New Scientist, 25 April 1998, p 20). So, prompted by Lucchesi's findings, doctors at the University of Michigan's hospitals are now investigating whether drugs that block the cascade will help patients suffering from cocaine overdoses.

Michael Davies of St George's Hospital in London, a cardiovascular pathologist and assistant medical director of the British Heart Foundation, says the Michigan team's research might explain why some young cocaine users develop a form of heart failure in which the heart grows floppy and pumps blood less efficiently. "This would fit quite well with the idea that complement is damaging blood vessels or heart tissue," he says.

Larry Alexander of Baylor Medical Center in Dallas, a drug abuse spokesman for the American College of Emergency Physicians, agrees: "The authorities should be doing more to highlight the danger cocaine poses to people's hearts."

Cocaine can also send coronary arteries into spasm. Alexander and other specialists in emergency medicine believe this is the reason for a growing number of young people turning up in hospital complaining of chest pain. The vast majority are men, and they are usually discharged after doctors establish that they are not suffering from a heart attack. Each case has to be thoroughly investigated, however, which stretches hospitals' resources.

"At the weekend I saw three young males in their early twenties with chest pains, and all three were positive for cocaine," says Alexander. "Normally it just goes away. But occasionally it gets very serious and you'll see a heart attack."

The link between chest pain and cocaine abuse isn't always clear, says Alexander. And this could mean that statistics on the number of emergency hospital visits caused by cocaine use (see below) are seriously underestimated. Alexander also fears that people who repeatedly send their cardiac arteries into spasm may suffer long-term heart damage.

John Henry, an expert on drug abuse at St Mary's Hospital in London, is similarly concerned. He suspects that up to 10 per cent of people reporting to hospital with chest pain owe their problems to cocaine abuse. Henry is seeking ethical approval to carry out anonymous urine tests for cocaine on everyone reporting to his hospital with chest pain.
-end-
Author: Michael Day
New Scientist issue 22nd January 2000


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