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Study Says Long Term Cannabis Consumption Enlarges Left Ventricle of Heart

Marc Moulin
left ventricle being checked by doctor

Are there cardiovascular health risks attached to consuming cannabis?

The left ventricle is one of the four chambers of the heart. It is responsible for pumping oxygenated blood out through the aorta to the rest of the body. As a critical coronary structure, an issue with the left ventricle could mean big health problems. An enlarged left ventricle, or left ventricular hypertrophy, can develop in response to high blood pressure or a heart condition that ultimately forces the left ventricle to work harder.

In the short-term, symptoms may include shortness of breath, chest pain, and dizziness. Long-term consequences of an enlarged left ventricle stroke or cardiac arrest. Preventing left ventricular hypertrophy might be as easy as finding time for exercise and eating a healthy diet, but new research also suggests that abstaining from cannabis could potentially help. That is, if the research is sound in the first place.

Regular Cannabis Consumption and an Enlarged Left Ventricle

The study, published recently in JACC Cardiovascular Imaging (2019), found that cannabis consumers were more likely to have a larger left ventricle. The researchers studied the association between cannabis consumption with cardiac structure and function. To do so, they used previously conducted cardiovascular magnetic resonance imaging on a sample of the U.K. population.

Participants self-reported their cannabis consumption and the researchers categorized them. The categories were “rare or never consumer” (no use or less than monthly consumption), “previous regular consumer” (weekly or daily consumption up to five years before the study), and “current regular consumer” (weekly or daily consumption within five years of the study).

The final analysis included 3,407 participants with a mean age of sixty-two years old. The numbers of regular and previous cannabis consumers were very low. They sat at forty seven and 145, respectively. It is possible that these numbers are statistically much lower than the true numbers of regular cannabis consumers. The illegal status of cannabis in the U.K., and the stigma attached to cannabis consumption, may have prevented some regular consumers from coming forward.

Nonetheless, the researchers found a link between regular cannabis consumption and a larger left ventricle when compared to rare or no cannabis consumption. Additionally, previous cannabis consumers had similar measures as rare/never users, suggesting that ceasing cannabis consumption can reverse the potential heart damage.

However, there are some serious research and real-world limitations to consider. These limitations throw the study’s suggestions into question.

left ventricle could be affected by this man's cannabis smoking

Lifestyle Factors and Cardiovascular Risk

The researchers adjusted for some important confounding factors such as tobacco smoking and alcohol consumption. However, some other lifestyle factors could play a significant role in developing an enlarged left ventricle.

These factors could be present among the rest of the population as much as among regular cannabis consumers. As mentioned earlier, diet and exercise can help prevent the condition. As such, a poor diet and lack of physical activity can lead to increased blood pressure, and related cardiovascular complications. Without measures for these other lifestyle factors, there is no way to rule out other causes.

Furthermore, the most popular method of cannabis consumption is smoking. The researchers adjusted for tobacco smoking, but could not adjust for cannabis smoking. Not all cannabis consumption methods are equally healthy. It is possible that if consumers used a less harmful consumption method, like a dry-flower vaporizer or oils, the same structural changes might not have occurred.

Quality Assurance and Illegal Cannabis

Although more affordable, it is difficult to know what is in illegal cannabis. According to a 2018 report, nine out of ten illegal cannabis farms in the state of California contain traces of potentially lethal pesticides. Of greatest concern is a pesticide called carbofuran which was originally intended to kill crop-eating insects. According to one researcher, just one-quarter teaspoon of carbofuran is enough to kill a bear.

This type of reporting raises serious concerns — what else is in illegal cannabis and what are the short and long-term effects on human health? The illegal status of cannabis in the U.K. may increase the likelihood of tainted cannabis products and their greater associated health risks.

Small Sample Size May Skew Results

Readers must also consider the results of this study in the context of their extremely small sample size. Furthermore, the results were based on retrospective, self-reported data, and categorized into two very generic cannabis-consuming groups.

Dividing consumers into “regular consumers” vs. “previous regular consumers” does not allow for the uncovering of a potential dose-response effect. For example, if consuming cannabis does enlarge the left ventricle, how much cannabis puts an individual at risk? These factors provide little confidence in the legitimacy of the findings.

left ventricle being checked by female asian doctor in lab coat

Does Cannabis Consumption Result in an Enlarged Heart?

Based on the available evidence, it is impossible to draw population-level conclusions. However, the results of this study deserve attention, and should be used to inform future research. Also, to ensure scientific validity, future studies need to collect large-scale prospective data from a diverse group of participants.

Although more difficult in countries without legal cannabis markets, researchers should collect data from participants who consume cannabis from a trusted source. We are at the beginning of understanding the true impacts, positive and negative, that cannabis can have on the human body. It is not a time to jump to conclusions, but a time to conduct well-designed research studies and make decisions based on rigorous scientific evidence.

References

Khanji, M. Y., Jensen, M. T., Kenawy, A. A., Raisi-Estabragh, Z., Paiva, J. M., Aung, N., … & Barutcu, A. (2019). Association Between Recreational Cannabis Use and Cardiac Structure and Function. JACC: Cardiovascular Imaging.
Pletcher, M. J., Vittinghoff, E., Kalhan, R., Richman, J., Safford, M., Sidney, S., … & Kertesz, S. (2012). Association between marijuana exposure and pulmonary function over 20 years. Jama307(2), 173-181.

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Marc Moulin
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