The recent death of Michael Ziobro in the United States, past and present medical studies, and the press have led the world to contemplate the association (if there is one) between medical cannabis use and cardiovascular disease

The studies cited in this article ask whether medical cannabis affects the heart and the cardiovascular system, and if so, what precautions can be taken to prevent cardiovascular disease in medical cannabis consumers.

Georgia State University Cannabis Study

A recent study focusing on the effects of cannabis use on cardiovascular and cerebrovascular mortality published in 2017 in the European Journal of Preventive Cardiology concluded that medical cannabis consumption “may increase risk for hypertension mortality.” To come to this conclusion, Yankey, Rothenberg, Strasser, Ramsey-White, and Okosun wanted to study whether people who mainly smoked cannabis ended up dying of cardiovascular diseases. Before delving into the research study, it’s important to point out that cardiovascular disease can be caused by any or all of the following correctable issues according to the Mayo Clinic:

  • Unhealthy diet
  • Lack of exercise
  • Obesity
  • Smoking

Yankey, et. al’s study compiled survey results from participants over the age of 19 who responded to cannabis consumption questions in the 2011 U.S. National Health and Nutrition Examination Survey. For fun and research, I filled out this questionnaire – here is a sampling of the questions on cannabis/marijuana:

  • How long has it been since you last smoked marijuana or hashish at least once a month for one year?
  • During the time that you smoked marijuana or hashish, how often would you usually use it?
  • During the time that you smoked marijuana or hashish, how many joints or pipes would you usually smoke in a day?
  • How long has it been since you last used marijuana or hashish?
  • During the past 30 days, on how many days did you use marijuana or hashish?

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These questions, coupled with cardiovascular health questions, were the basis for the Yankey, et. al study. There were 1,213 eligible study participants, 72.5 percent of whom were “presumed to be alive.” This presumption decreases the study participants by about 25 percent. The study found that cannabis users in the study were three times as likely to die from cardiovascular complications or diseases than people who did not consume cannabis.

The study also stated that “increased duration of marijuana use is associated with increased risk of death from hypertension.” The study refers to recreational cannabis in the last line of the abstract, but the U.S. CDC survey does not ask study participants whether they consume medical or recreational cannabis, so this is an assumption that is probably incorrect in numerous instances.

Issues with Cannabis & Cardiovascular Mortality Study

One issue with this study is that, while the cannabis questions are specific to cannabis and the tobacco questions are separate, the two are not separate in the cardiovascular questionnaire. This means that cardiovascular issues in the study participants could be the results of tobacco smoking or consumption only and have nothing to do with cannabis consumption and the researchers would never know.

The study states that the researchers “controlled for cigarette smoking and other relevant variables” but does not say how or what the other variables were. How could researchers separate out the effects of cigarette smoking and cannabis smoking if a study participant did both? Also, the CDC survey itself does not specify the difference between medical cannabis and recreational cannabis consumption, so it’s impossible to know, as the researchers indicated in the abstract, that “recreational marijuana use potentially has cardiovascular adverse effects.”

In conclusion, while smoking medical cannabis may have adverse effects on one’s cardiovascular system in the long-term, this study does not prove that people who consume medical cannabis or any other type of cannabis are at higher risk of death from cardiovascular diseases and issues, simply because all other factors cannot be ruled out in causing these deaths. Also, medical cannabis is not always smoked, and it is unlikely that medical cannabis tinctures have the same effect on the cardiovascular system that smoking does.

Franz & Frishman’s 2016 Cardiovascular Disease & Cannabis Study

For accurate information, Franz and Frishman’s 2016 study might be a better read and a more solid study. The study researched “the effects of cannabis smoking on the vasculature and occurrence of cardiovascular (CV) events such as myocardial infarction (MI) and stroke.” The study’s approach to studying cannabis’ effects on cardiovascular disease is also focused on participants who consume “marijuana cigarettes” and not patients who consume any other type of medical cannabis.

Franz and Frishman’s study did find that smoking cannabis increases “heart rate, supine systolic and diastolic blood pressures” and “sympathetic nervous system activity.” The study found that these symptoms in angina patients (severe chest pain often spreading to shoulders, arms, and neck caused by inadequate heart blood supply) may cause faster exercise-induced angina. Put plainly, Franz and Frishman are saying that in patients with angina, angina symptoms may increase after smoking a “marijuana cigarette.” This tells us nothing about the effects of other types of medical cannabis, nor does it tell us anything about people who consume medical cannabis and do not have angina.

St. Luke’s 2014 Stress Cardiomyopathy & Cannabis Study

In 2014, CNN reported on a study of 210 patients (1% of the hospital patients tracked) from St. Luke’s University Hospital Network in Fountain Hill, Pennsylvania, U.S. Dr. Amitoj Singh, the lead investigator in the study, noted that “many reports of heart attacks, strokes, and the two cases of” stress cardiomyopathy have been linked to marijuana.” Dr. Singh was concerned by the study results, because the group at highest risk for cardiovascular disease were at low risk for acute stress, hypertension, diabetes, migraines, and hyperthyroidism, and yet “they still had high cardiac risk.”

The study found that cannabis consumers were twice as likely to have heart attacks or abnormal heath rhythms, and twice as likely to develop stress cardiomyopathy. The connection between the cannabis consumers in the study and tobacco use, illicit drug use, and depression was not studied but might have contributed to the patients’ likelihood of myocardial issues. All in all, the problem with studies like these are that all the variables are not controlled for – proving that cannabis or medical cannabis causes heart disease requires much more rigorous research studies that measure participants’ consumption habits on many different levels.

The work being done in Israel with frequent medical cannabis studies and patient database compilation is a fantastic place to start.

[Image credit- Wikimedia Commons]

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