Pot Impacts Heart, Study Shows
WebMD News Archive
March 2, 2000 (San Diego) -- The Woodstock generation is getting some very
bad news: Marijuana smoking in middle age may trigger a heart attack in those
who still indulge. Marijuana smokers increase their risk of having a heart
attack almost five times within one hour of lighting up, according to a study
presented here at an American Heart Association (AHA) meeting.
"This is the first documented link between marijuana and heart
attack," says Murray A. Mittleman, MD, PhD, of Beth Israel Deaconess
Hospital in Boston.
Mittleman tells WebMD the spike in risk quickly decreases after an hour
passes. Pot smokers are twice as likely as nonsmokers to have a heart attack
one to two hours after lighting up.
To put that increased risk in perspective, Mittleman says that the risk of
heart attack increases 100 times when a couch potato decides to shovel snow,
and it "increase[s] 2.5-fold with sex."
AHA president Lynn A. Smaha, MD, PhD, tells WebMD that he will share the
findings with colleagues, such as cancer specialists, who may be prescribing
medical marijuana to treat nausea and poor appetite. "Any drug has the
potential for adverse side effects," says Smaha. He says marijuana should
be approached with the same caution as that used with other drugs.
A third of the patients studied by Mittleman and colleagues were women, and
the age range was 20 to 92. The patients were interviewed three days after
having a heart attack. The interviews were designed to determine any possible
contributing factor during the days and weeks leading up to the heart attack,
according to Mittleman.
Of the nearly 3,900 people Mittleman studied, about 3% reported being
regular marijuana users. Thirty-seven said they smoked marijuana within 24
hours of the heart attack, and "nine patients said they used it within an
hour of [the onset of symptoms]," says Mittleman.
Smaha says it is clear that "more research needs to be done to delve
into the mechanism at work here." Mittleman agrees and says that his study
doesn't provide enough information to determine whether it is marijuana itself
that is causing the increased risk or whether it is associated with other
elements in the smoke, such as carbon monoxide. He says it is clear that
"inhaled fine particles have adverse health effects." But the risk
appears to be limited to older marijuana smokers. "Most of the regular
marijuana users in the study were in their 40s and 50s and the oldest was
Mittleman did note some interesting differences between the users and
nonusers of marijuana. Those who had smoked marijuana prior to having a heart
attack were much younger, with an average age of 44 compared to 62 in the
nonsmokers. Also, the marijuana users were less likely to have other risk
factors for heart disease, such as high blood pressure and diabetes, and were
less likely to have had a history of chest pain prior to the heart attack, says