Less than a week after seven new states legalized recreational or medical cannabis use, several researchers at the American Heart Association’s annual scientific conference in New Orleans were all too prepared to deliver a major buzzkill. On Nov. 13, cardiologists from St Luke’s University of Pennsylvania presented a new study to the heart confab which they say finds that younger cannabis users were twice as likely to develop stress cardiomyopathy over non-users. The condition, also known as ‘broken heart syndrome’, is a sudden but typically temporary weakening of the heart muscle which induces symptoms resembling those of a heart attack—including chest pain, dizziness, and shortness of breath.
Researchers began by examining the medical records of 33,343 Americans who were hospitalized with stress cardiomyopathy between 2003 and 2011, which they found through combing the patient data of the National Inpatient Sample, the nation’s largest database on hospital stays. Out of this group, 210 individuals (less than one percent overall) were identified as cannabis users either through patient-provided information in their medical file or by testing positive for recent use through urinalysis.
The rare affliction of broken heart syndrome, from which most recover within a day without repeated occurrence, has only proven fatal in extraordinary circumstances, as it can sometimes precipitate cardiac arrest. It was originally discovered in Japan, and has since been confirmed to most prevalently affect older women experiencing emotionally stressful events such as the passing of loved ones or divorce. Traditional cardiovascular risk factors, such as high cholesterol, elevated blood pressure, and diabetes, increase susceptibility to stress-induced cardiomyopathy, but it’s also been tied to depression and other mental health complications.
Yet what is already known about stress cardiomyopathy is precisely what makes the findings of St. Luke's research team most striking: while the syndrome is more commonly experienced by older women, the patients who used marijuana were more likely to be younger, male, and with fewer conventional risk factors like hypertension or obesity. Furthermore, cannabis users were more likely to go into cardiac arrest, as well as to require a pacemaker to correct resulting abnormal heart rhythms.
The study’s lead investigator, Dr. Amitoj Singh, was inspired to parse this population by at least two documented cases in medical literature of stress cardiomyopathy related to cannabis use; “There have been many reports of heart attacks, strokes and the two cases of [stress cardiomyopathy] that have been linked to marijuana,” Singh told CNN. He added that expanding access to marijuana, particularly for unsupervised recreational use, has raised the interest of the medical community about marijuana’s potential cardiac risks. Existing research on this subject to date is somewhat contradictory: some studies have found increased incidence of cardiovascular troubles among cannabis users, while others have illustrated that marijuana’s primary compounds of THC (tetrahydrocannabinol) and cannabinoids may act to decrease blood pressure—leading some to coin the medical conundrum “the marijuana paradox.” However regarding this particular study’s implications, co-author Dr. Sahil Agrawal was unequivocal, stating, “This development of stress cardiomyopathy in younger patients who used marijuana suggests a possible link that needs to be further investigated.”
However there are several important caveats to the results of this study which should temper any reader’s potential alarm until more can be learned. Firstly, cannabis users in the sample were more likely than nonusers to have histories of depression, psychosis, anxiety disorder, alcoholism, tobacco use, and broader substance abuse, with these factors potentially enhancing the risk of broken heart syndrome; but the researchers did adjust their model to account for such co-factors, and still found a “statistically significant relationship between the drug and stress cardiomyopathy,” said Singh. Secondly, given that this study is retrospective and uses previously collected samples, researchers have no idea how frequently these patients were using cannabis or the amount of time elapsed between usage and incidence of the syndrome. Thirdly, given that a national population of medical data was inspected, with state-by-state breakdowns unavailable, no inferences can be drawn about whether cannabis-related heart problems are increasing in states which have legalized it.
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While studies such as this one raise interesting questions for users about the plant’s oft supposed harmlessness, definitive answers will continue to be elusive as long the federal prohibition on marijuana, which has serially impeded scientific research into both the harms and benefits of cannabis use, persists in America. The Onion of course found humor in the study’s conclusions, reporting the reaction of Treacy Lerman, recipe developer, to the news: “I knew I was actually dying that one time.”