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Friday, 3 March, 2000, 03:28 GMT
Cannabis 'increases heart attack risk'
Cannabis smoker
Smoking cannabis may be risky
The risk of a heart attack is greatly increased by smoking cannabis, scientists say.

The finding comes shortly after separate studies found that the active ingredient in cannabis can shrink cancer tumours, and ease some of the symptoms of multiple sclerosis.

In the new study, US scientists found that smoking cannabis could increase the risk of having a heart attack nearly five-fold within an hour of taking the drug.


These effects may pose significant risk, especially in people with unrecognised coronary disease

Dr Murray Mittleman, Beth Israel Deaconess Medical Center, Boston
The researchers studied information on cannabis use from 3,882 middle-aged and elderly patients who had suffered heart attacks.

A total of 124 patients were identified as current users, including 37 who reported smoking the drug up to 24 hours before their attack, and nine who had used it within an hour of experiencing symptoms.

The researchers, from the Beth Israel Deaconess Medical Center in Boston, Massachusetts, found that in the first hour after taking cannabis, the heart attack risk was 4.8 times higher than during periods of non-use.

In the second hour, the risk dropped to 1.7 times higher.

Dr Murray Mittleman, director of cardiovascular epidemiology at the medical centre, said: "To my knowledge, this is the first study to document that smoking marijuana can trigger a heart attack.

"It increases the heart rate by about 40 beats per minute. It also causes the blood pressure to increase when the person is lying down, and then abruptly fall when the person stands up, often causing dizziness.

"These effects may pose significant risk, especially in people with unrecognised coronary disease."

Although individual risk was lower than it was from cocaine, Dr Mittleman said, the overall threat to public health could be greater because cannabis use is so widespread.

How cannabis may trigger a heart attack is unknown.

Dr Mittleman said it was unclear whether the cause lay with the active ingredient of cannabis - THC - or other components in the smoke such as carbon monoxide, or a combination of the two.

The findings will be presented to the American Heart Association's 40th Annual Conference on Cardiovascular Disease Epidemiology and Prevention in San Diego, California.

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See also:

01 Mar 00 |  Health
Cannabis 'helps MS sufferers'
14 Sep 99 |  Medical notes
Drugs factfile
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