Can Smoking Weed Double Your Risk of Heart Attacks?

3 min read

Can smoking weed double your chances of having a heart attack?

Yes.....but there's more to this answer.

A study published in the Canadian Medical Association Journal states that young adults who smoke cannabis have double the chances of having a heart attack compared to those who don't smoke.

But there's more to this than meets the eye.

The authors of the study came to their final results by comparing and analysing survey data from over 33,000 young adults(18-44) in the US, collected by the Centers for Disease and Control in 2017 and 2018.

So What's The Deal?

The study in the Canadian Medical Association Journal found that those who had smoked cannabis(four or more times) in the previous month had a slightly higher chance of suffering a heart attack compared to those who didn't smoke cannabis.

Approximately 1.3% of the group that smoked cannabis in the previous month reported having a myocardial infarction(heart attack), as compared to 0.8% of people from the group that did not smoke cannabis.

The study indicates that 61 people out of 4610 cannabis users (1.3%) and 240 people out of 28 563 non-users (0.8%), reported heart attacks.

A report in CNN, published in September 2021, compares these two numbers to state that cannabis use can double heart attack risk.

While that's TECHNICALLY true, it fails to clearly establish the difference between absolute risk and relative risk.

Absolute What and Relative What?

The study compares young adults who recently smoked cannabis to those who don't smoke cannabis.

(Photo: iStock)

Absolute risk and relative risk.

Absolute risk is the actual risk or possibility that you will have a heart attack in the course of your life.

Relative risk is your risk in comparison to others' risk, or in this case, Group A's risk, compared to Group B's risk.

Group A, which was made of cannabis smokers, reported a 1.3% rate of heart attacks, while Group B, reported a 0.8% rate of heart attacks. The difference between the two groups, in reality, is just 0.5%.

This is also because young adults have a relatively lower heart attack risk than older adults.

But while the absolute risk difference between the two is just 0.5%, when you look at relative risk, the group of cannabis smokers has a 62.5% higher chance of having a heart attack than the group of non-smokers!

So technically, yes, weed smokers are more than twice as likely as non-smokers to have a heart attack.

But the fact that the relative heart attack risk in young adults who smoke cannabis is more than double than non-smokers is only because the prevalence of heart attacks in young adults is very low already.


So Is Smoking Weed Safe?

Smoking weed or any plant matter can damage the lungs.

(Photo: iStock)

Ingesting the fumes from burning anything, including plant matter, can damage your lungs.

Apart from the damage to your lungs, Dr Karim Ladha, the lead author of the study also noted that previous research points at cannabis use altering users' heart rates.

"When someone's heart rate becomes irregular, it can increase the amount of oxygen the heart needs. Simultaneously, cannabis can also limit the amount of oxygen delivered to the heart, which can lead to a heart attack."
Dr Karim Ladha, Lead Author

Dr Ladha is a clinician-scientist and staff anesthesiologist at St. Michael's Hospital and the University of Toronto in Canada.

Speaking about smoking cannabis he adds, "There's increasing evidence that this could be harmful to you, both in the short term and the long term."

But, more real-time research is essential to draw a conclusion, he says. Real-time research is challenging because of different marijuana laws in different parts of the world.

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