Cannabis Use May Cause Structural Changes In The Heart

Are you a regular user of cannabis? Whether it’s for claimed medical benefits (which won’t be argued here) or recreational use, marijuana, or cannabis, is rapidly becoming mainstreamed. Here in the States, the rush to legalize, commercialize and, of course, tax marijuana use is nothing short of mad.

One might argue that with a federal government (and most state governments) so dysfunctional and out of touch with what constituents really need and want, keeping them high might not be a bad idea. But is legalization, sale and widespread use of cannabis really a good idea? Should we be doing more research into possible negative side effects (as well as benefits) before we rush to make pot a commercial and recreational reality?

In a previous article, I wrote about research findings related to teen cannabis use and resulting depression and neuropsychiatric disorders in adulthood. You can read that article right here.

Now comes another reason to give pause before rushing to light up. Researchers at Queen Mary University of London have identified a possible link between cannabis use and structural changes to the heart. According to their findings, cannabis use can actually alter the structure and function of the heart. Pretty serious, don’t you think?

The team analyzed MRI images from the UK Biobank population study. They found an association between regular use of marijuana and an enlarged left ventricle, as well as early signs of heart function impairment. The left ventricle is the heart’s main pumping chamber.

The results are published in JACC Cardiovascular Imaging.

Lead author Dr Mohammed Khanji, Senior Clinical Lecturer at Queen Mary, said: “Our findings are not conclusive but the research took place against a backdrop of decriminalisation and legalisation of recreational cannabis use in many countries. We urgently need systematic research to identify the long-term implications of regular consumption of cannabis on the heart and blood vessels. This would allow health professionals and policymakers to improve advice to patients and the wider public.”

The researchers analyzed the cardiac scans of 3,047 people with an average age of 62, none of whom had cardiovascular disease. While the overwhelming majority had rarely or never used pot, there were 105 who had used it regularly, but not in the five years previous to the study. There were another 47 who were current and regular users.

What they found among the 47 was that they were more likely to have enlarged left ventricles. They also exhibited the early signs of heart function impairment. This impairment was measured by how the heart muscle fibers deformed during contraction.

The other three chambers of the heart showed no changes in size or function. Across all three groups, no significant differences in overall mass of the left ventricle or the ejection fraction, or amount of blood ejected from the chambers with each heartbeat.


One piece of good news came from the group that hadn’t used marijuana in the previous five years. They had similar heart size, shape and function to the group that had rarely or never used. That tells us that cessation of use should be followed by restoration of heart health, as long as there are no other mitigating factors like pre-existing heart disease.

This study is reminiscent of a previous study which linked marijuana use with the increased risk of stroke and heart failure. That study, published in 2017, found a 26 percent increased risk of stroke and a 10 percent increased risk of heart failure in regular marijuana users.

While the Queen Mary University study accounted for such factors as age, smoking and alcohol consumption, as well as blood pressure and diabetes, Dr. Khanji recognized the study’s limitations. He noted that Caucasians were over-represented, for example. There were also a relatively low number of regular cannabis users in the study. It was also reliant on self-reporting about the use of a drug that is still illegal in Great Britain.

However, Dr Khanji, also a consultant cardiologist at Newham University Hospital and Barts Heart Centre, part of Barts Health NHS Trust, said: “We believe this is the first study to systematically report changes in heart structure and function associated with recreational cannabis using cardiac MRI, which is a very sensitive imaging tool and the current reference standard for assessing cardiac chambers.

The World Health Organization has warned about the potential harmful health effects of non-medical cannabis use and called for more research specifically around the cardiac impact.”

Perhaps we should slow our roll, so to speak, when it comes to making cannabis mainstream and widely available. We may well be setting ourselves up for significantly more medical problems down the road.

Keep the faith and keep after it!

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Journal reference – Mohammed Y. Khanji, Magnus T. Jensen, Asmaa A. Kenawy, Zahra Raisi-Estabragh, Jose M. Paiva, Nay Aung, Kenneth Fung, Elena Lukaschuk, Filip Zemrak, Aaron M. Lee, Ahmet Barutcu, Edd Maclean, Jackie Cooper, Stefan K. Piechnik, Stefan Neubauer, Steffen E. Petersen. Association Between Recreational Cannabis Use and Cardiac Structure and Function. JACC: Cardiovascular Imaging, 2019

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