As marijuana legalization spreads across the United States and other parts of the world, concerns about its safety are growing. Two recent studies have added to the growing evidence that cannabis use may significantly increase the risk of heart attacks, even among younger and otherwise healthy adults. Researchers published these findings in JACC Advances and presented them at the American College of Cardiology’s Annual Scientific Session (ACC.25) after conducting a retrospective analysis of roughly 4.6 million people.
Cannabis Use Linked to Increased Heart Attack Risk
The first study found that cannabis users under the age of 50 were more than six times as likely to suffer a heart attack compared to non-users. Researchers used data from TriNetX, a global health research network, to track cardiovascular outcomes over an average follow-up period of three years. The study revealed that cannabis users faced a 6 times greater risk of cardiovascular attacks, a 4 times increased risk of ischemic stroke, a 2 times greater likelihood of suffering heart failure, and a 3 times greater likelihood of becoming victims of cardiovascular death.
All participants in the study were under 50 years old and had no significant cardiovascular comorbidities at the time of conducting the study. They also had healthy blood pressure and cholesterol levels, no diabetes, and no history of tobacco use or coronary artery disease. Despite these favourable health profiles, the findings suggest that cannabis use alone may pose a significant threat to heart health.
The second study, a meta-analysis of 12 previously published research studies, pooled data from over 75 million people. This analysis, the largest of its kind to date, found that active cannabis users were 1.5 times more likely to suffer a heart attack compared to non-users. Seven of the 12 studies included in the meta-analysis showed a significant positive association between cannabis use and heart attack incidence, while four found no significant difference, and one showed a slightly negative association.
Why Cannabis May Harm the Heart
While the exact mechanisms through which cannabis affects the cardiovascular system remain unclear, researchers have proposed several theories. Cannabis may disrupt heart rhythm regulation, increase oxygen demand in the heart muscle, and contribute to endothelial dysfunction, a condition that impairs blood vessels’ ability to relax and expand. One study included in the meta-analysis found that the risk of heart attack peaked about one hour after marijuana consumption, suggesting an acute effect on the cardiovascular system.
Dr. Ibrahim Kamel, the lead author of the retrospective study and a clinical instructor at Boston University, emphasized the importance of understanding these risks. “Asking about cannabis use should be part of clinicians’ workup to understand patients’ overall cardiovascular risk, similar to asking about smoking cigarettes,” he said. “At a policy level, a fair warning should be made so that the people who are consuming cannabis know that there are risks.”
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Limitations and the Need for Further Research
Both studies have limitations that warrant caution in interpreting their findings. The retrospective nature of the analysis means that researchers cannot fully establish exact causation, only correlation. Also, the meta-analysis faced challenges in accounting for other potential factors, such as the duration and amount of cannabis use or the concurrent use of tobacco and other drugs.
“We should have some caution in interpreting the findings in that cannabis consumption is usually associated with other substances such as cocaine or other illicit drugs that are not accounted for,” Dr. Kamel noted. “Patients should be forthcoming with their doctors and remember that we are their number one advocate, and having the full story matters.”
Prospective studies, which follow participants over time, are needed to confirm these findings and identify which groups may face the highest risk. Such research could also help clarify the specific ways in which cannabis affects the cardiovascular system and whether certain forms of cannabis (e.g., smoked, vaped, or edibles) carry different levels of risk.
Growing Use of Cannabis in the United States
The findings come at a time when cannabis use is rising in the United States, particularly in states where the drug is legal for recreational use. The increasing availability and social acceptance of marijuana have led to higher rates of consumption, even among older adults. However, this trend has raised concerns about the potential long-term health consequences, particularly for the heart.
What Should Consumers Do?
Given the growing evidence linking cannabis use to heart problems, health experts advise caution. Dr. Kamel recommends that clinicians routinely ask patients about cannabis use as part of their cardiovascular risk assessment. He also urges policymakers to ensure that consumers are adequately informed about the potential risks.
For individuals who use cannabis, it is essential to be honest with healthcare providers about consumption habits. “Patients should be forthcoming with their doctors and remember that we are their number one advocate, and having the full story matters,” Dr. Kamel said.
Conclusion
While marijuana legalization has brought many benefits, including reduced incarceration rates and increased tax revenue, it has also raised important public health questions. The latest research underscores the need for greater awareness of the potential cardiovascular risks associated with cannabis use, particularly among younger adults.
As scientists continue to investigate the mechanisms behind these risks, consumers should remain informed and cautious, and policymakers should prioritize public health in their decision-making. For now, the message is clear: cannabis may not be as harmless as it seems, and its impact on heart health deserves serious attention.
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