The effects marijuana has on heart health is not as cut-and-dried as it might seem. Like many other health-related topics in the cannabis space, research is preliminary.  Unfortunately, there is no scientific consensus, but there are some interesting studies being done that help us gain an understanding on how marijuana could affect the heart.

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The ECS Regulates Heart Health

The endocannabinoid system (ECS) is a neuromodulatory system comprised of cannabinoid receptors CB1 and CB2, endocannabinoids, and enzymes that metabolize those endocannabinoids. CB1 and CB2, molecular pathways that facilitate the signaling from neurotransmitters to the brain, are located throughout the body.  CB1 receptors are located in the central and peripheral nervous system while CB2 receptors are located in most organ systems, including the cardiovascular system. In fact, researchers believe that the ECS plays a role in the regulation of heart rate and blood pressure.  According to a 2017 Journal of Thoracic Disease review by Hermant Goyal, Hamza Awad, and Jalal Ghali, a team of researchers out of the Mercer University School of Medicine in Georgia, the ECS induces multiple cardioprotective events including: 

  • Hypotension. THC reduces blood pressure by activating TRPA-1 channel while anandamide (an endocannabinoid) can independently reduce blood pressure by activating vanilloid VR1 receptors.
  • Anti-inflammatory effects to the cardiovascular system. CB2 receptors are located throughout the cardiovascular system and appear to reduce the severity of tissue inflammation and injury as a result of cardiovascular disorders. 

The seemingly cardioprotective role of the ECS has made the neuromodulatory system a target for the treatment of diseases such as heart failure, stroke, myocardial infarction, atherosclerosis, and restenosis. 

Cannabis Use and Cardiovascular Risk

There is a plethora of work out there that can tend to be confusing with claims being made on both sides. In 2018, an independent review conducted by authors from multiple prestigious universities attempted to analyze the observational studies dealing with cannabis and cardiac/metabolic disorders. The studies chose enrolled adults using any form of marijuana, and focused on risk factors including:

  • Diabetes
  • Cholesterol and lipid disorders
  • Obesity
  • Stroke
  • Myocardial infarction (heart attack)

The strength of the evidence was independently assessed by reviewers. The review looked at 24 studies from 1975 to 2017 that looked at cannabis use in relation to cardiovascular risk factors and their clinical outcomes. Of these, six studies suggested a metabolic benefit from using cannabis.  However, these studies are hard to base a consensus off of because they didn’t look at populations over a long period of time. The rest of the studies found insufficient evidence that marijuana use affect heart attacks, stroke, diabetes, and elevated lipid levels.   Ultimately, the report concluded that the studies were littered with poor data and therefore inconclusive.

woman getting her blood pressure checked Source: iStock

Cannabis Abuse and Heart Attacks

A 2019 study published in the Mayo Clinic Proceedings, found that the males who abused cannabis in their study “had a higher prevalence of cardiovascular risk factors.” The study also found:

  • Cannabis abuse was significantly associated with heart attacks
  • The highest risks were more pronounced risk in young and middle age groups
  • Those who abuse cannabis also had higher prevalence of hypertension, coronary artery disease, dyslipidemia, diabetes, obesity, and more.

Cannabis’ Potential Post-Heart Attack Benefits

Looking at a different angle, in 2018, a report was released from the University of Colorado’s Division of Cardiology. It looked at hospital outcomes of repeat heart-attack patients and divided them into those who reported cannabis use versus those who reported no-use.  Strikingly, the study found that marijuana use prior to a heart attack was associated with decreased in-hospital mortality post-heart attack. Another study published in 2018 showed similar results.  Paradoxically, the study found that cannabis users admitted for heart attacks were:

  • On average, 10 years younger than non-users
  • More likely to be placed on mechanical ventilation during their hospital stay

The fact is that there are many explanations possible to the above paradoxical results including:

  • Those who consume cannabis tend to be younger
  • “Smoker’s paradox” (the phenomenon where there are less deaths among tobacco users in a 30-day period after a heart attack). could also apply to cannabis users. 
  • “Marijuana use may have provided a cardioprotective effect to users” 

Conclusion

Additional study is warranted to further investigate these discoveries and to identify potential mechanisms by which cannabis use is associated with our cardiovascular health.  It’s clear that we have a long way to go to uncover the full cardiac effects of cannabis use.