Diseases & Conditions

Known Medical Benefits, But Marijuana Use Also Tied to Risk of Stroke and Heart Failure

By on 03/13/2017


For a lot of patients, medical marijuana has well-known benefits, such as relief from debilitating pain, but does this mean that it is risk-free?

Not necessarily, according to new research scheduled for presentation this week at the American College of Cardiology’s 66th Annual Scientific Session. Aditi Kalla, MD, Cardiology Fellow at the Einstein Medical Center in Philadelphia, is the study’s lead author.

The new research suggests a significant relationship between marijuana use and an increased risk of stroke and heart failure.

We asked Dr. Kalla some questions about the study’s findings.

Your research links marijuana use with increased risk of heart failure and stroke. What suggested to you that this would be a timely research topic? Was it the increasing legalization of marijuana for medicinal purposes?

AK: That’s correct. As of the recent 2016 election, decriminalization of cannabis passed in several states bringing the total count up to 28 states (including Pennsylvania) and D.C. where cannabis is now legal for medicinal and/or recreational purposes. From a physician’s perspective, we now need to be more knowledgeable regarding the risks and benefits of cannabis as patients may request a prescription for it. It is rare that a drug has “hit the market,” so to speak, without undergoing clinical trials to determine safety and efficacy, hence we sought out to study the effects (positive or negative) on the cardiovascular system.

Your study suggests that marijuana use was associated with a 26 percent increase in the risk of stroke and a 10 percent increase in risk in the development of heart failure. Those are some pretty big numbers. Did those numbers surprise you? Did you think the risks would be so significant?

AK: These numbers were definitely unexpected! The most intriguing fact is that cannabis use was associated with significant increased risks of heart failure and cerebrovascular accidents (which is most often a stroke) even after taking into account traditional cardiac risk factors. In other words, cannabis use alone was an independent risk factor for having heart failure or a stroke.

The study suggests that other risk factors, like obesity, high blood pressure, alcohol use and smoking, were linked to marijuana use, but didn’t account for the increased risk that you found in your research. How did you isolate marijuana alone as a risk factor?

AK: We used a statistical tool called multivariate regression analysis which allowed us to take into account the differences between cannabis users and non-cannabis users in regards to age, sex, and rates of traditional cardiac risk factors including hypertension (or high blood pressure), diabetes, hyperlipidemia (or high cholesterol), tobacco use, alcohol use, and coronary artery disease. Once we accounted for these differences between the two groups (cannabis users versus non cannabis users), cannabis users still had higher risks of having heart failure or a stroke.

Your study included patients with a wide age range, 18 through 55. Was there any difference in risk of heart failure and stroke, depending on age? Were the older users more at risk than younger users?

AK: In our study population, the average age of cannabis users and non-cannabis users was 33 years old and 26 years old respectively. We did not assess risks for either heart failure or stroke based on age.

Your research was based on hospital records. Do we need more research on how people use marijuana outside that setting?

AK: One of the limitations of our study is that we did not have information regarding the amount, form of consumption, or reason (recreational versus medicinal) cannabis was used. As cannabis gets legalized across the country, we anticipate a greater ability to conduct further research to investigate how the amount and form of cannabis used affects the cardiovascular system.

It sounds like we don’t know for sure how marijuana might increase the risk of heart failure and stroke, but we have some ideas. What are they?

AK: One explanation of how cannabis affects the heart has to do with cannabis receptors that are found on heart muscle cells. Scientists have found that activating these receptors decreases the heart muscle cell’s contractility (or ability to squeeze) which in turn means the heart as a whole would not pump well and this can lead to heart failure. We do not know exactly how cannabis use may lead to strokes, however medical case reports have suggested blood clots resulting in strokes may have formed in patients using a high dose of cannabis.

Does the fact that there are cardiovascular risk factors negate the potential benefits for treatment of cancer chemotherapy nausea, multiple sclerosis, chronic pain, seizure disorders and other conditions? Or would prescribing its use become essentially like prescribing any other drug for which there are potential risks as well as potential benefits?

AK: We believe the latter is true. Every medication has its intended effects and side effects. Our study highlights that cannabis may have cardiac side effects. In light of this, patients using cannabis for any purpose may need to be monitored more carefully for potential cardiac complications.

Your findings sound as if there are benefits for physicians who find themselves having a discussion with patients about marijuana use. Do you think this is a discussion they need to have?

AK: I believe so. Based on the results of our study, using cannabis may increase one’s risk of having heart failure or a stroke. It is important for patients to be aware of these risks as lifestyle modification plays a significant role in preventing and treating cardiovascular complications.

  1. Wilfredo Vargaspadilla


    That is a big lie. Cannabis have been used for many years without the consequences that this research suggests. Stroke and heart disease are caused by excessive consumption of fats an a very poor diet. A simple plant as Marihuana has no fat at all. THC and derivates don’t cause it. Smoking regular cigarettes with the already known 5,000+ chemicals that it produces and very well known by the medical, federal and cigarrettes producer companies does and still on the market for the longest. The issue is not the pros and cons of Marihuana use, it is all about who can control it and who its going to get the biggest piece of the pie from the money it will produce.

  2. George Servais


    Dubious study at best and was it peer reviewed? I now too many long term regular users that are healthy as horses and quite a few that are in bad shape. In every case the ones worse off were worse off due to poor life choices. This smells too much like the propaganda that was pushed when it was first banned. I am not a user myself.

  3. Peter Simmons


    The only relevent fact we need to consider is ‘the study was based on hospital discharge records ‘. Despite this, terms such as research are used as if there actually was research, when the reality is this is an examination of stats which may or may not show a link, but shows no causality whatsoever, is not science but fiddling around with stats, and is totally unscientific because science is supposed to be about seeking truth, attempting to disprove a thesis, whereas this person clearly set out to find something to use against cannabis, anything, and her spuriousw tactics are blatantly biased. A disgraceful way for anyone to behaviour, especially someone claiming to be part of science.
    This comes as cannabis is being found by real researchers to have an expanding range of benefits for human illnesses and medical conditions, far too numerous to keep listing, and I suspect the pharmaceutical industry is involved somewhere along the line in its attempts to slow down legalisation until they have exploited the plant for every high priced ‘treatment’ they can squeeze out of it.
    I was wondering if the newly released, onscenely expensive, ‘wonder cure’ for heart disease which also strangely cuts cancer, canakinumab, could possibly be another, it seems too coincidental to have the cana prefix otherwise. This is what it’s all about, high profits, cannabis must be scary to capitalists since it’s cheap and freely available, with patients even able to grow their own medicine. Not what big Pharma wants.

    I would be interested in the list of sponsors of this ‘study’.

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