Heart attacks more common among young adults who use marijuana—but a key question remains
Young adults who regularly use marijuana are much more likely to have had a myocardial infarction (MI), according to new data published in Canadian Medical Association Journal.
"With recent legalization and decriminalization, cannabis use is increasing in young adults in North America, and we do not fully know its effects on cardiovascular health," lead author Karim Ladha, MD, a clinician scientist at Unity Health Toronto, said in a press release. "We found an association between recent cannabis use and MI, which persisted across an array of robust sensitivity analyses. Additionally, this association was consistent across different forms of cannabis consumption, including smoking, vaporization, and other methods such as edibles. This suggests that no method of consumption is safer than another in this regard."
The study included more than 33,000 adults between the ages of 18 and 44 years old. Seventeen percent reported using marijuana in the past 30 days. Data was extrapolated from the 2017 and 2018 cohorts of the American Behavioral Risk Factor Surveillance System, a survey of U.S. adults.
According to the authors, a history of MI was reported by 1.3% of marijuana users and 0.8% of nonusers.
Also, compared with nonusers, the prevalence of recent marijuana use was higher among males, unmarried respondents, current combustible cigarette users, current e-cigarette users and heavy alcohol drinkers.
MI were also more common when marijuana occurred more than four times per month.
"The large sample size, generalizability and detailed data on cannabis consumption of this cross-sectional study provide unique insight into this growing public health concern” David Mazer, MD, a clinician scientist at Unity Health Toronto, said in the same press release. “Further studies and more data are needed to confirm these findings and elucidate the mechanisms contributing to cannabis-associated cardiovascular outcomes.”
An important limitation
One of the study's key limitations is that researchers lacked information on what, exactly, came first: the marijuana use or the heart attack.
“We were unable to differentiate between participants who began using cannabis before having an MI, and those who began using cannabis after having an MI,” the authors wrote. "However, the plausibility of our association is strengthened by a similar association between recent cannabis use and history of stroke from the same data set. Additionally, MI leading to cannabis use (reverse causation) is unlikely, and the elevated odds observed among more frequent users may provide evidence of a biologic gradient for this association. Regardless, healthcare professionals need to be aware that a relationship between any recent cannabis use and history of MI exists."
Read the full study here.