Long-term cannabis use may not increase heart attack risk, new study finds—but many questions remain

The regular use of cannabis does not increase a middle-aged adult’s risk of experiencing a heart attack, according to new data published in the American Journal of Cardiology.[1] In fact, the study suggests the recent use of cannabis may even be linked to a reduced risk of such adverse events.

However, these findings should not necessarily be taken as proof that marijuana is good for the heart. Researchers are still learning how to study this subject, and plenty of previous trials have suggested cannabis use could be quite harmful.

For this latest analysis, specialists with the University of California, San Diego (UCSD) tracked data from nearly 10,000 adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 2009 to 2018. All participants were between the ages of 35 and 59 years old, and the mean age was 47.3 years old.

Overall, 24.9% of respondents reported a history of monthly cannabis use that lasted longer than one year. The mean age was 48.1 years old, and 74.6% of the group was white. The most common frequency among respondents was nine to 24 times per month, followed by 25 to 30 times per month.

Participants with a history of at more than one year of monthly cannabis use were more likely to be white men with “less education, lower household income and more days of alcohol use per week” than participants who never use cannabis. They were also much more likely to be current cigarette smokers and presented with a “significantly higher” 10-year atherosclerotic cardiovascular risk disease (ASCVD) risk score.

On the other hand, this group reported engaging in more physical activities per week than participants who never touch cannabis.

Meanwhile, a history of myocardial infarction (MI) was reported by 2.1% of all respondents and 3.2% of respondents with a history of monthly cannabis use. In fully adjusted multivariable models, however, a history of monthly use preceding an MI was not associated with an increased MI risk.

“The lack of association in our study may be unexpected given the observation that those with a history of cannabis use were more likely to be male, smoke more cigarettes, drink more alcohol, and have a greater 10-year ASCVD risk,” wrote first author Jamie Corroon, ND, MPH, a clinical researcher with UCSD and founder of the Center for Medical Cannabis Education, and colleagues. “In contrast, they were also found to engage in more physical activity. Other observational studies, including some using NHANES data, have reported that cannabis users engage in more physical activity and have more favorable BMI profiles, lower concentrations of selected lipid biomarkers, and better glycemic parameters. It remains unclear whether these favorable factors counterbalance potential risks.”

Another noteworthy takeaway from this analysis was the fact that, among participants with a history of monthly cannabis use, individuals who had not used it recently faced “significantly greater odds” of experiencing a MI than more recent users. This was “somewhat unexpected,” Corroon et al. wrote, “given the known acute cardiovascular effects of cannabis use, other studies reporting associations with recent use and the shorter duration of exposure in this group.”

What did the authors make of this finding?

“It is conceivable that subjects with a history of monthly cannabis use may have ceased usage earlier owing to health-related concerns that may have otherwise contributed to an increased risk of CVD,” they wrote. “If this phenomenon exists, it may be comparable to the ‘smoker's paradox’ evident in tobacco research, in which cigarette smokers may receive more intensive medical interventions at a younger age and consequently exhibit better outcomes than do current smokers or never smokers. This finding warrants further investigation.”

The authors concluded by calling for additional research on this topic, especially studies that can do a more exact job of quantifying cannabis use among test subjects, tracking the potency of any cannabis products being used, etc.

“Given the expanding access to cannabis products in the United States and around the world, more research, particularly longitudinal and experimental studies, is needed,” the group wrote.  

Another perspective on cannabis use and cardiovascular health

Kristie M. Harris, PhD, a health psychologist with Yale School of Medicine, wrote a separate commentary about these findings for the American Journal of Cardiology.[2]

“Investigation of the cardiovascular effects of cannabis use is of particular importance given the distribution of cannabinoid 1 receptors in the myocardium, aorta smooth muscle and vascular endothelium, and the well-documented effects of acute cannabis use on physiological processes associated with cardiovascular risk, including greater sympathetic nervous system activation, endothelial dysfunction and oxidative stress,” Harris explained. “How this translates into risk for major cardiovascular events, such as MI, remains unclear however, largely due to methodological limitations of currently available data.”

Harris noted that much more clinical research is needed that examines the potential long-term impact cannabis may have on a person’s health, especially as access to cannabis continues to increase throughout the United States. She also noted that tobacco use is an ongoing problem for research teams trying to examine this topic, creating challenges that the industry is still looking to solve.

“Our understanding of the cardiovascular effects of cannabis use is in its nascent stage, and more rigorous, prospective, longitudinal study is needed to understand the discrepancy between Corroon et al.’s findings and earlier mechanistic studies on acute cannabis effects and epidemiological studies of recent use and MI risk,” she wrote. “Such investigations should also more accurately reflect the current landscape of cannabis products which has evolved rapidly since the period of observation in Corroon et al.—with greater access and commercialization leading to expanded routes of administration and more potent formulations.”

Michael Walter
Michael Walter, Managing Editor

Michael has more than 16 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.

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