Marijuana Use, Cardiovascular Complications Linked In New Study

04/23/2014 04:59 pm ET
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A new study from France shows an association between marijuana use and heart-related complications.

The findings are based on data from the addictovigilance system in France, which includes cardiovascular-related complications associated with marijuana use between 2006 and 2010. During this time period, there were 1,979 marijuana-related reports to the addictovigilance network, 35 of which had to do specifically with cardiovascular-related complications. The percentage of cardiovascular complications related to marijuana tripled from 2006 to 2010, going from 1.1 percent to 3.6 percent.

Study researcher Émilie Jouanjus, Pharm.D., Ph.D., of the Centre Hospitalier Universitaire de Toulouse in France, explained that the scientific community generally considers marijuana's cardiovascular effects to not be associated with serious health problems for most young and healthy users. But this new study did unearth some serious cardiovascular problems in cannabis users,

However, because of the sparse available data, "it is not possible to tell whether it is because marijuana-related cardiovascular problems are actually sparse or because it is on the contrary undetected and rather under-reported, in which case we would be facing a major public health problem," Jouanjus told HuffPost.

Marijuana exposure was daily for nearly half of the patients -- 16 -- while eight of the patients reported marijuana exposure of once or more in the last 12 months, and six reported one to nine exposures to marijuana in the last 30 days. Researchers were only able to gather information on duration of marijuana use for five of the patients, for whom duration of use ranged from two years to more than 25 years.

The average age of those experiencing marijuana-related cardiovascular compilations was 34.3 years and 16 of the total 35 patients had either a personal or family history of heart problems. Researchers found that nine of the 35 patients had a personal cardiovascular history -- including high blood pressure and acute coronary syndrome -- and seven additional patients had a family history -- including close family members who experienced stroke, coronary disease and vascular disease. Twenty-one of the patients also smoked tobacco.

Twenty of the cardiovascular complications related to marijuana were acute coronary syndromes; other complications included disease related to arteries in the limbs or arteries in the brain. Ultimately, nine of the patients died.

Considering how many people in France are estimated to be regular marijuana users -- around 1.2 million -- only a "small proportion of complications was reported to the French addictovigilance system," the researchers noted in the Journal of the American Heart Association study. However, the number of cases is likely extremely underestimated. "The reporting rate of adverse drug reactions is estimated to be 5% in the field of pharmacovigilance," the researchers wrote. "In other words, 95% of cases are usually not captured."

The study's researchers noted that they were limited by incomplete information -- data was only available for some of the study participants' body mass index, for instance; the same goes for family history of heart disease. Given this, it's impossible to prove that marijuana actually causes cardiovascular problems.

While it's still not entirely known how marijuana could affect the cardiovascular system in particular, it's known that it exerts its effects on the body through compounds called phytocannabinoids, or exocannabinoids, which then bind to specific cannabinoid receptors in the brain, heart, vessels and other tissues and organs. "The endocannabinoid system is known to be important in the modulation of many vascular functions," Jouanjus explained, but how exactly marijuana could lead to cardiovascular disorders is still a matter of debate. More study is needed to determine if exocannabinoids act differently in people who have pre-existing heart problems.

In a related editorial, Drs. Shereif Rezkalla, M.D., of the Marshfield Clinic, and Robert A. Kloner, M.D., Ph.D., of the University of Southern California Keck School of Medicine, pointed out that data on marijuana-related cardiovascular events is likely underreported because people may not be inclined to report illicit drug use to their doctors or hospitals.

Rezkalla and Kloner also pointed out that more research is needed to fully understand the safety of marijuana use. While there is evidence that marijuana can help some people manage pain and other conditions, evidence also exists showing that marijuana use could be associated with cardiovascular risks and even death.

"We strongly suggest a national system for mandatory reporting of medical complications related to marijuana use," they wrote in the editorial. "It is the responsibility of the medical community to determine the safety of the drug before it is widely legalized for recreational use. It is also important to educate health care providers and the public of the potential risk of developing a cardiovascular event associated with the use of marijuana."

However, it's important to keep in mind that the study simply shows preliminary evidence of marijuana's potential harm on heart health -- the findings aren't conclusive, noted Dr. Allen J. Taylor, M.D., a professor of medicine at the Georgetown University School of Medicine.

"The study's limitations are important in that we can't know how high the risk is, just that there is a signal of risk between marijuana smoking and heart troubles," Taylor said in a statement provided to HuffPost. "However, it is a shame that we simply don't know more about a substance that potentially carries the risk of serious bodily harm. It seems that public perception is ahead of the science. We should remain open to the scientific facts as they evolve."

Indeed, Dr. Valentin Fuster, M.D., director of Mount Sinai Heart and Physician-In-Chief of Mount Sinai Hospital, said in a statement provided to HuffPost that the evidence is still not clear as to whether marijuana is "more risky than tobacco cigarette smoking or less, but one thing is clear, it’s affecting young people."

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