Cannabis and the Heart: Clinicians Weigh in on Risks and Realities
A new meta-analysis raises questions—clinicians weigh in on what we really know about cannabis and cardiovascular events
One Year Ago, We Hosted A Journal Club Discussion On The Cardiovascular Concerns Surrounding Cannabis. So, What’s Changed Since June 2024?
A recent systematic review and meta-analysis by Storck et al., published in Heart (2025), has reignited concerns around the cardiovascular risks of cannabis. Synthesizing data from 24 studies, the authors reported statistically significant associations between cannabis use and major adverse cardiovascular events (MACE), including a 29% increased risk of acute coronary syndrome (ACS), a 20% increase in stroke risk, and more than double the risk for cardiovascular mortality. The reaction in the media was swift and alarmist, but the study’s nuance—and its limitations—deserve closer inspection. To better understand how this research intersects with real-world care, I asked clinicians for their thoughts. Their responses reveal both caution and critique—and raise fundamental questions about how we interpret population-level cannabis data.
Associations, Not Answers
Several clinicians were quick to point out what the study itself acknowledged: most of the underlying evidence comes from cross-sectional or retrospective cohort designs, limiting our ability to draw causal conclusions.
“I feel like we are stuck with only being able to make observations and associations with these types of studies,” said Dr. Erica Seas, a general practitioner. “There are too many variables left unaccounted for… Remember, there was a time we thought alcohol caused lung cancer before we figured out it was a confounder.”
Dr. Seas will, however, use the latest data to inform patient interactions, “In my practice going forward, I will consider educating patients with heart disease about these ‘observations’ and then let the patients decide whether they want to change their habits.”
Dr. Louis Lux, an internal medicine physician and hospice specialist, emphasized the importance of distinguishing recreational from medical use. “Most people in the study likely were smoking high-potency recreational cannabis—not low-dose, non-combustible formulations used in medical contexts. Jumping to conclusions about medical cannabis is premature and reckless.”
Their message was clear: while the meta-analysis aggregates large volumes of data, it doesn’t resolve key questions about the role of route, dose, or product type.
Route, Dose, and the Individual
Clinicians who work directly with cannabis patients stressed that product formulation and administration method are central to both efficacy and safety—yet these variables were largely absent from the studies reviewed.
“Dosing, formulation, and route of administration matter a great deal,” said Jesse Christianson, DNP. “I steer clients away from combustibles and focus on education around lower-risk routes like vaping whole flower.”
Dr. Jordan Tishler, president of the Association of Cannabinoid Specialists, emphasized moderation. “It is reasonable to assume that high doses pose more risk, and lower, medically oriented doses pose less. These studies don’t control for dose or exposure, which is vastly important.”
This disconnect between what patients are actually using—and how they’re using it—versus what’s reported in population studies remains a major barrier to actionable conclusions. Future studies need to include more data points about the amount and type of cannabis-product use.
A Web of Confounding Factors
For some respondents, the study triggered deeper questions about biological mechanisms and lifestyle confounders.
Dr. Janice Makela, who specializes in geriatric medicine, noted, “The American diet is very omega-6 heavy, which pushes our endocannabinoid systems into overdrive. I wonder about the interaction between high-THC cannabis and a pro-inflammatory diet.”
She also referenced the ongoing CARDIA study, which has not shown increased cardiovascular risk among cannabis users. “The jury is still out,” she concluded.
Len Kamen, MD, shared a balanced opinion about confounding factors and available data, “I do think that individuals who smoke anything these days have a higher risk, and I advise against it. I manage patients with known cardiac disease who use medical marijuana.”
Dr. Kamen doesn’t seem to have witnessed a correlative morbidity or mortality with that group, although, he says, “I have concerns and inform them prior to certification [for medical use] of this concern. I still think there are too many other mitigating factors and have some skepticism about how this data was collected by the time heart disease shows up in the adult population.”
Ultimately, he states that, “There have been multiple exposure points that could raise their risk assessment.”
These reflections highlight the complex interplay of dietary, genetic, pharmacologic, and behavioral factors that influence how cannabis affects the cardiovascular system—none of which are easily captured in a meta-analysis.
Practice Implications: The Real Question
If the association is real, what should clinicians actually do with this information?
Dr. Phil Molloy, who has decades of experience in internal medicine, posed this dilemma plainly: “Do I identify high-risk cardiovascular patients in my practice and proactively bring up cannabis, just like I do with tobacco or cholesterol?”
Molloy admits that, to date, he had not incorporated cannabis into those risk discussions—but believes that should change. “I recommend that HCPs assume this is a real association. Now what? There will never be a prospective RCT addressing this.” Molly urges HCPs to bringing up cannabis proactively in discussions with patients, “just like we do for other risk factors.”
He also raised practical concerns: how can busy clinicians identify relevant patients? Can electronic health records flag high-risk individuals who might benefit from a conversation? And ultimately—would such interventions actually change patient behavior?
A pragmatic stance—one that acknowledges the imperfect evidence while advocating for cautious patient education—may become the dominant clinical posture.
Meta-Analyses Are Maps, Not Oracles
Dr. Daniel Stein, a neurologist, put it succinctly: “This is the problem with meta-analysis. No new, reliable conclusions can be drawn since the source studies are inhomogeneous.”
Yet he praised the authors for acknowledging this limitation and avoiding overstatement. “Storck et al. do not confuse coincidence with causation… Too bad numerous media headlines do not see it that way.”
He also pointed to reference #8 in the paper—a 2018 review on the cardiovascular effects of synthetic cannabinoids—and reminded us that THC is a partial CB1 agonist, not a full one like the synthetic drugs K2 or SPICE. “Nonetheless, we need to remain open-minded to the possibility that high-potency THC products could trigger adverse events not observed in the last 5,000 years…”
Conclusion: Between Signal and Noise
The Storck meta-analysis is not the first paper to suggest a link between cannabis and cardiovascular events—and it won’t be the last. What it does is sharpen the conversation, refocus attention on patient safety, and reveal how urgently we need better data. The good news is that cannabis use is a potential modifiable risk factor. For example, providing guidance on the risks of various administration forms.
More than anything, this paper reminds us of the ongoing challenge in cannabis medicine: how to bridge the gap between population-level associations and individualized care. Until we have stronger longitudinal data with precise exposure characterization, clinicians must navigate with both caution and context—and remain open to perspectives that challenge both fearmongering and complacency.
Questions for the Clinicians Reading this:
· How do these findings compare to your clinical experience?
· Do they change how you talk to patients with cardiovascular risk factors?
· Are there limitations or confounders in this research that you feel should be emphasized?