Cannabis use doubles the risk of death from cardiovascular disease, according to a study.

Cannabis use is linked to a doubling of the risk of dying from cardiovascular disease , with a significantly higher risk of suffering a stroke or acute coronary syndrome - a sudden reduction or blockage of blood flow to the heart - according to a pooled analysis of real-world data, published online in the journal Heart .

Cannabis and cannabinoid use has skyrocketed in the last decade, researchers note. The legalization of cannabis in certain jurisdictions and the expansion of its use for medicinal purposes have likely changed people's risk perceptions of the drug and contributed to its growing popularity, they suggest.

Although previously published studies have linked cannabis use to cardiovascular problems, the magnitude of the risk has not been clearly defined. This is an important gap in light of recent major changes in use and the increased potency of the drug, they add.

To strengthen the evidence base, the researchers therefore scoured research databases for large observational studies, published between January 2016 and December 2023, that explored cannabis use and serious cardiovascular outcomes: death from cardiovascular disease; and non-fatal acute coronary syndrome (to include heart attack and stroke ).

From an initial set of 3012 articles, 24 involving approximately 200 million people were included in a pooled analysis of the results: 17 cross-sectional studies, 6 cohort studies, and 1 case-control study.

Most study participants were between 19 and 59 years old. And in studies where gender was recorded, cannabis users tended to be predominantly male and younger than non-users.

The analysis revealed increased risks associated with cannabis use: a 29% increased risk of acute coronary syndrome; a 20% increased risk of stroke; and a doubled risk of dying from cardiovascular disease.

The researchers acknowledge that there was a moderate to high risk of bias in most of the included studies, largely due to a lack of reporting of missing data and imprecision in cannabis exposure measures. Furthermore, most of the included studies were observational, making it impossible to draw causal conclusions from the data. Several used the same data.

Despite these caveats, the researchers say theirs is a comprehensive analysis of published data on the potential association between cannabis use and major cardiovascular diseases, and provides new insights from real-world data .

In a related editorial, Professor Emeritus Stanton Glantz of the University of California, San Francisco, and Dr. Lynn Silver of the Oakland Institute of Public Health and the Department of Epidemiology and Biostatistics at the University of California, San Francisco, say the study "raises serious doubt about the assumption that cannabis poses few cardiovascular risks."

Clearly, more research is needed to clarify whether cardiovascular risks are limited to inhaled products or extend to other forms of cannabis exposure, they suggest. Cannabis is now generally more potent and has diversified into a wide range of high-potency inhaled cannabis concentrates, psychoactive synthetic cannabinoids, and edibles , they note.

"It is necessary to clarify how these changes affect cardiovascular risk, as well as the proportion of risk attributable to the cannabinoids themselves versus particulate matter, terpenes, or other components of exposure," they state.

They conclude: " Cannabis should be incorporated into the framework for clinical cardiovascular disease prevention. Similarly, cardiovascular disease prevention should be incorporated into the regulation of cannabis markets. Effective product warnings and risk education should be developed, required, and implemented.

"Cardiovascular and other health risks must be taken into account in the regulation of product design and permitted marketing as the evidence base grows. Currently, such regulation focuses on establishing a legal market, woefully neglecting the minimization of health risks.

"Specifically, cannabis should be treated like tobacco : not criminalized, but discouraged, with protection for passersby from secondhand exposure," they propose.