‘Concerning’ findings cast doubt over perceptions the drug is relatively harmless.
Not all green and leafy things are good for your heart.
Cannabis use is becoming increasingly popular, with many countries moving to legalise its recreational and/or medicinal use on the back its perceived harmlessness. But little is known about the long-term risks of cannabis use, especially on the cardiovascular system.
Now, a new population-based, cross-sectional study from the US reports daily cannabis use is associated with a 28% increase in the odds of adverse cardiovascular outcomes. The findings were published in the Journal of the American Heart Association.
“It’s concerning whenever we identify a modifiable risk factor, where people might not be having heart events if they weren’t doing it,” said Dr Elizabeth Paratz, a cardiologist from St Vincent’s Hospital in Melbourne.
“It really raises the question of whether we should be trying to reduce society’s use of cannabis, given it seems to be having a [negative] impact on the heart.”
Researchers explored whether cannabis use over the previous 30 days was linked with coronary heart disease, myocardial infarction and stroke in a nationally representative sample of 430,000 adults aged 18 to 74 years.
Four per cent of the sample used cannabis daily, 7% had used cannabis at some point in the past 30 days, and 89% were non-users. Sixty-one per cent of the sample had never smoked tobacco cigarettes.
Compared to non-users, daily cannabis use was associated with a 25% increase in the odds of MI, a 42% increase in the odds of stroke and a 28% increase in the odds of the composite cardiovascular outcome (i.e., CHD, MI or stroke) after controlling for relevant factors such as tobacco cigarette use, age, sex, BMI, diabetes and physical activity. There was no association between daily cannabis use and CHD.
Related
Similar associations between daily cannabis use and adverse cardiovascular outcomes were observed when the analysis was limited to people who had never smoked tobacco cigarettes, as well as those who had never used tobacco cigarettes or e-cigarettes, which Dr Paratz described as “concerning”.
A dose-response relationship between cannabis use and adverse cardiovascular outcomes was also reported, with increasing usage associated with greater risk of MI, stroke and the composite outcome.
The researchers suggest THC, the active component of cannabis, exerts a haemodynamic effect via the endocannabinoid receptors located throughout the cardiovascular system.
Dr Paratz said she felt the researchers only asking about cannabis use, rather than a broader range of illicit drugs, was a potential limitation to the study.
“We know things like methamphetamines are bad for the heart, and if we knew people were taking cannabis but not methamphetamines, for example, that would further strengthen the cannabis association,” she said.
Dr Paratz recommended GPs should not make assumptions about potential cannabis usage among their patients.
“We see cannabis use across the age, gender and socioeconomic spectrum, so routinely asking all patients [about cannabis use] should be the standard,” she told TMR.
“But it’s not enough to know people are using cannabis, quantifying the usage as much as possible is also important to provide an estimate of how much risk they may have.”
Journal of the American Heart Association 2024, online February 28
