Editor's Note: Media fearmongering on marijuana is a decades-old tradition. Look closely at the arguments, read the texts of the studies and science they're based on, and the truth of the situation is often that a fraction of the danger is posed to public health, if at all. Paul Armentano, one of America's leading experts on the properties and science of cannabis dissects the latest unfounded hype about heart-risks posed by cannabis consumption.

Is pot smoking likely to trigger fatal heart attacks? You might think so after reading recent headlines like these:



FoxNews.com: Marijuana use may lead to heart attack complications, death, study says



Los Angeles Times: Potential for heart attack, stroke risk seen with marijuana use



CBS News: Marijuana use may lead to cardiac arrest and other heart problems



Daily Mail: Cannabis increases heart problems and may even prove fatal for young and middle-aged users



Is there any legitimacy to these scaremongering headlines? Predictably, that’s where things start getting murky.



The impetus for the mainstream media’s most recent fixation with the alleged dangers of pot is a French study, published online in the Journal of the American Heart Association. Investigators reviewed data collected by the French Addictovigilance Network, a national database of adverse case reports involving psychoactive substances, between the years 2006 to 2010. Researchers compiled all of the available reports specific to cardiovascular complications (such as heart attack, hardening of the arteries, or stroke) and cannabis.



Among the 9,936 total drug-related cases in the database, authors identified 35 cases (0.4 percent) in which both cardiovascular complications and cannabis were referenced. Eighteen of these cases resulted in hospitalization and nine resulted is death. Patients in this sample were mostly men, with an average age of 34.



Not surprisingly, a more detailed look into these 35 cases finds numerous limitations in the available data as well as several potentially cofounding variables – all of which cast serious doubt in regards to whether cannabis played a significant role, or any role, in these adverse outcomes. Notably, even though the authors state in the study’s abstract, “We report and analyze 35 recent remarkable cardiovascular complications following cannabis use,” the full text of the paper reveals that subjects in eight (23 percent) of these cases had only consumed cannabis one or more times within the past year. Six others had reported using cannabis more than once but fewer than nine times during the 30-days prior to their complications.



The remaining 16 subjects were characterized by the authors as “regular or daily” users – a classification defined by investigators as “10 or more uses in the last 30 days”. Nonetheless, it is unclear whether these subjects used cannabis in the hours prior to any adverse event. Toxicological analyses identified THC, marijuana’s primary psychoactive compound, in only 13 of the 35 total cases. (However, because THC is lipid soluble, it may potentially be detected in the blood of habitual consumers at low levels for several days after past use, though it possesses a shorter half-life in occasional users.) In the other 22 cases, no toxicology result was available; cannabis was simply referenced in the subjects’ medical file. In all but three cases, marijuana was referenced in conjunction with other substances, some of which are well associated with health risks, such as cocaine, alcohol, tobacco, and opiates.



A further look into the patient histories of these 35 subjects reveals additional cause for skepticism. Twenty-one (60 percent) of the subjects smoked tobacco – a substance long-established to elevate the risk of cardiovascular complications. Nine subjects (26 percent) possessed pre-existing cardiovascular complications, and seven subjects (20 percent) had a family history of cardiovascular disease.



Yet despite these limitations, the authors concluded, “Practitioners should be well aware that cannabis may be a potential trigger factor in cardiovascular complications in young people.”



However, if inhaling cannabis is a legitimate trigger for heart disease or stroke, one would presume that investigators would have identified far more than 35 cases referencing cannabis in conjunction with adverse cardiovascular events. (On this point, authors concede, “Another possible explanation for the small number of cases is that cardiovascular disorders may hardly be connected to cannabis considering the lack of evidence-based data in this area,” which appears to be a polite way of stating that actual evidence in support of the authors’ hypothesis that pot causes heart attacks doesn’t exist.) In fact, the authors themselves estimate that 1.2 million French citizens are “regular or daily” users of the plant – virtually none of which, self-evidently, are experiencing spontaneous adverse cardiovascular events due to their cannabis consumption.



With an estimated 150 million people consuming pot worldwide it is somewhat surprising that the study’s investigators and the journal’s editors would raise an alarm over such an infinitesimally small number of problematic cases in which cannabis may (or may not have) played a role. (By comparison, consuming non-steroidal anti-inflammatory drugs such asIbuprofen – particularly in larger quantities – is proven to increase risks of heart failure and other adverse cardiovascular events three-fold.) It seems even odder that the mainstream media would care, much less promote headlines implying that smoking pot poses any sort of a significant risk factor for heart attacks and death.



This is not to say that marijuana, in rare instances, doesn’t possess the potential to trigger adverse cardiovascular effects. Cannabinoids play a significant role in cardiovascular regulation – meaning that manipulation of this system has the potential for both potentially positive (The administration of cannabidiol has been shown to be neuroprotective in an animal model of stroke, for instance.) and unfavorable outcomes. Cannabis consumers for decades have been aware that the substance may temporarily elevate heart rate (a condition known as tachycardia, which sometimes results in ER visits) But more regular pot smokers typically develop tolerance to this physiological effect.



A 2001 review of nearly 4,000 heart-attack patients by Harvard Medical researchers identified nine cases where subjects had reported smoking pot in the previous hour (though authors acknowledged that in three of these nine cases, subjects also engaged in other high-risk behaviors during the preceding hour as well.) Investigators concluded, “Smoking marijuana is a rare trigger of acute myocardial infarction and may pose a health risk to patients with established coronary artery disease and perhaps to individuals with multiple coronary risk factors.” (For years NORML has cautioned on its website, “[T]hose who have a history of heart disease or stroke may also be at a greater risk of experiencing adverse side effects from marijuana.”) By contrast, a 2013 prospective study assessing the survival rates of 3,886 heart attack survivors over an 18-year period concluded that cannabis’ potential risk in this population did not reach the level of statistical significance.



The bottom line is that no recreational intoxicant or therapeutic agent is completely safe. But cannabis is objectively safer than most available, legal alternatives. That said, it is prudent to caution patients with coronary heart disease and those at high risk for cardiovascular disease from smoking pot (or anything else), and to encourage more systematic studies into its potential association with cardiovascular complications. But expressing such concerns simply reaffirms that the ongoing criminalization of cannabis and its consumers is a disproportionate and unjustified public policy response to what is, at worst, a public health concern – not a criminal justice issue.