March 26, 2025 from Medscape
New Research Highlights Cannabis–Heart Health Link
Two recent studies are adding weight to concerns about the cardiovascular impact of cannabis. The first, a retrospective study published in JACC Advances, and the second, a meta-analysis to be presented at the American College of Cardiology’s annual meeting, both suggest that cannabis use may significantly elevate the risk of heart attack and stroke — even among healthy young adults.
Lead author Dr. Ibrahim Kamel of Boston University emphasized that the key takeaway is that legalization does not equate to safety. As he stated,
“We studied healthy, young adults. If they had this significant risk, I would speculate that the risk of cannabis would be higher in patients with hypertension and older patients.”
A Sixfold Risk Increase for Heart Attack
The retrospective study drew on data from approximately 4.6 million patients across the U.S., Canada, and the EU. Researchers matched cannabis users and nonusers by age, sex, race, and health factors such as blood sugar, cholesterol, and BMI. All participants were free of major cardiovascular risk factors.
Despite this, cannabis users had:
- A sixfold increased risk of heart attack
- A fourfold increased risk of ischemic stroke
- Double the risk of heart failure
- Triple the risk of cardiovascular death, heart attack, or stroke
Researchers couldn’t determine dosage thresholds or whether different methods of consumption — smoking, vaping, or ingesting — carried different levels of risk. However, a sub-analysis found that alcohol and cocaine use did not affect the results, further strengthening the cannabis-specific correlation.
Meta-Analysis: 1.5 Times Higher Heart Attack Risk
Dr. Kamel also led a meta-analysis pooling data from 12 studies — 10 from the U.S., one from Canada, and one from India. Seven studies found increased risk, four showed no difference, and one found lower risk among cannabis users. Overall, cannabis users were 1.5 times more likely to experience a heart attack.
Most of these heart attacks were thrombotic rather than due to plaque rupture, suggesting that cannabis may impair endothelial function and blood flow — a theory consistent with the observed vascular effects in other studies.
Calls for Warning Labels and Patient Education
Despite limitations in accounting for substance use and cannabis dosage, the studies underscore the need for clearer public health messaging. Dr. Kamel believes cannabis products should include health warnings akin to those on tobacco.
He argued,
“We shouldn’t be expected to prove that cannabis use is harmful. The industry should have to prove that cannabis use is safe.”
Physicians, he added, have a duty to inform patients — even when causality isn’t fully established.
“Patients should be informed,”
Kamel said, pointing to the growing body of evidence connecting cannabis use to heart disease risk.
As cannabis legalization expands, so does the responsibility to communicate its risks — especially when those risks may not be immediately obvious to younger, otherwise healthy users.
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