STUDY FINDS USING MARIJUANA UPS HEART ATTACK RISK

WASHINGTON (Reuters) - The risk of a heart attack jumps nearly
five-fold during the first hour after smoking marijuana, posing a
particular threat to middle-aged users of the drug, according to a
study released on Monday.

Researchers led by Dr. Murray Mittleman, director of cardiovascular
epidemiology at Beth Israel Deaconess Medical Center in Boston,
interviewed 3,882 people who had suffered a heart attack as part of a
study of factors linked to the ailment.

The likelihood of suffering a heart attack was 4.8 times greater in
the first hour after smoking marijuana when compared to periods of
non-use of the drug, Mittleman found. In the second hour after
smoking the drug, the risk was 1.7 times greater. Starting in the
third hour after smoking marijuana, no significant risk rise was
documented.

Increasing numbers of people in their 30s, 40s and 50s are marijuana
users, as members of the post-World War II baby boom generation who
may have started using the drug in the 1960s and 1970s trek through
middle age, experts said. Men beginning at about age 45 and women a
few years later are at paramount risk of a heart attack.

Mittleman said that while the increased risk may be negligible for
young marijuana users, it could be deadly for people already at
higher risk by virtue of their age or other risk factors.

``I think the message is that for individuals who are entering the
age group where coronary disease is prevalent -- particularly if they
have established coronary disease or have multiple risk factors --
that they should think about whether it's reasonable to continue
smoking marijuana given that it does pose a real health risk to those
individuals,'' Mittleman said in an interview.

The study appears in the journal Circulation, published by the
American Heart Association (news - web sites).

More Dangerous Than Sex

Smoking marijuana was far less risky as a heart attack trigger than
using cocaine, which raises the risk 25-fold during the first hour
after use, the study found. The heightened risk from marijuana was
roughly equivalent to vigorous exercise for someone of average
fitness, and more dangerous than sexual intercourse for a sedentary
person.

Some 124 patients in the study (116 men and 8 women) reported having
smoked marijuana during the year prior to their heart attack. Their
average age was about 44, with nearly a quarter of them aged 50 to
69. Nine said they had smoked marijuana within an hour before their
heart attack.

Marijuana use may trigger a heart attack in one of several ways, said
Mittleman, also an assistant professor at Harvard Medical School
(news - web sites) and Harvard School of Public Health. He noted that
smoking marijuana raises heart rate.

``We know that after smoking a single marijuana cigarette, there is a
dose-dependent increase in heart rate, typically a doubling in heart
rate is not at all surprising. There are also complicated effects on
blood pressure,'' Mittleman added.

It may initiate a heart attack by causing a plaque inside a coronary
artery to rupture and form a clot, which can block the flow of blood
to the heart muscle, the researchers said.

Marijuana use is also linked to a rise in the heart's demand for
oxygen, while simultaneously lowering the supply of oxygen in the
blood.