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Cocaine cardiology: problems, mysteries.

Cocaine cardiology: Problems, mysteries

As more and more cases of cocaine-relatedheart problems and deaths are recognized, researchers are beginning to get an idea of what types of heart disease the drug causes. But how the damage occurs, who is prone to problems and why so few users are affected remain a mystery, says Jeffrey M. Isner of Tufts University in Boston.

Isner, one of the first to publish in thescientific literature on the connection between cocaine and heart disease, is studying the physiological correlation between the two. He discussed some of the cases and their possible causes at last week's American Heart Association Science Writers Forum in Monterey, Calif.

Of the U.S. cases reported so far, three-quartershave been heart attacks and the rest were due to inflammation or arrhythmia. The problems occurred immediately after cocaine use, and none of the users had discernible underlying conditions that might have predisposed them to heart disease.

Isner and his colleagues' description ofseven cases in the Dec. 4, 1986, NEW ENGLAND JOURNAL OF MEDICINE followed previous reports of 26 other incidents. Since he published, Isner says, at least four more cases have appeared and details of 19 more have been submitted for publication. Most of the people had snorted "normal" levels of the drug.

While researchers don't know how cocainecauses heart attacks, they are beginning to rule things out. Spasms in the coronary arteries and subsequent formation of a blood clot at the spasm are believed capable of causing heart attacks in non-users, but users are evidently not especially prone to such spasms.

Using a diagnostic test routinely usedto test for coronary artery spasms, Isner and his colleagues, as well as researchers at several other laboratories, checked nine cocaine users who had suffered heart attacks. In the test, a drug that can cause spasms in susceptible people is injected via catheter directly into the coronary arteries. If the test shows the person to be sensitive to the drug, naturally occurring spasms are presumed to be causing the heart problems.

Isner and his colleagues tried the sametest with cocaine after obtaining consent in a user with heart problems. Again, no signs of spasms were seen.

Some researchers have also linkedcocaine use to myocarditis, or inflammation of the heart muscle. Isner has checked a tissue biopsy from someone with cocaine-related myocarditis and found an unusually large number of a certain type of white blood cell. The cells are characteristic of cardiac hypersensitivity to some therapeutic drugs, suggesting that an allergic reaction may be to blame for cocaine-related myocarditis.

Researchers are at a loss to explain theepidemiology of the association. Although the number of reports linking cocaine to specific instances of heart disease has been rising over the past five years, it is still extremely small compared with the estimated 5 to 6 million cocaine users in the United States. The apparent increase in the rate firms up the relationship, Isner says, but why the drug's effect on the cardiovascular system of most users is limited to a boosting of the heart rate and blood pressure, while a small percentage get heart disease, is unknown. "This is something that's going to affect a distinct minority of users," says Isner. "But we don't have any way of predicting who is going to belong to that subset.

"The drug has an awfully long history. It'sstill used by millions of Indians in Peru and Colombia. And at least in that population, the potential for sudden, fatal cardiac disorders has not been described or recognized." One potential source of the difference -- impurities in the U.S. street product -- has not been checked because of the difficulty of obtaining samples of the drugs used by the patients, he says.
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Author:Silberer, Joanne
Publication:Science News
Date:Jan 31, 1987
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