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Two new studies suggest that cannabis use can raise your risk of heart failure, heart attack, and stroke. Dmitry Tishchenko/Getty Images
  • Two preliminary studies found that cannabis use increased the risk of major adverse heart and brain-related events.
  • One study looked at the risk of heart attack and stroke while hospitalized among older cannabis users who also had risk factors for cardiovascular disease.
  • In the other study, researchers examined the risk of heart failure among daily cannabis users, compared to non-cannabis users.

Older adults who use cannabis had a higher risk of a major cardiovascular event such as a heart attack or stroke while hospitalized, compared to a similar group of non-cannabis users, according to a preliminary study presented Nov. 6 at the American Heart Association Scientific Sessions in Philadelphia.

In a second non-published study from the same meeting, people who use cannabis daily had a greater chance of developing heart failure, compared to those who never used cannabis.

“These studies clearly demonstrate that those who more frequently use marijuana develop worse heart disease outcomes, particularly people with comorbidities, such as diabetes and high blood pressure,” said Dr. Benjamin J. Hirsh, director of preventive cardiology at Northwell Health’s Sandra Atlas Bass Heart Hospital at North Shore University Hospital.

He was not involved in either of the new studies.

How much of this impact is due to the harmful effects of cannabis itself or to related behaviors, such as lack of exercise or poor nutrition, still needs to be studied, he added.

But there appears to be an association between the use of marijuana and heart disease, Hirsh told Healthline.

The American Heart Association (AHA) recommends that people avoid smoking or vaping any substance, including cannabis products, because of the possible harm to the heart, lungs and blood vessels.

Loren E. Wold, PhD, a professor in the Department of Surgery at The Ohio State University, said the heart-related effects of cannabis are likely to due to both inhaling smoke or vapor and compounds in cannabis such as THC or their breakdown products.

He was not involved in either of the new studies.

“Particulate matter levels are vastly increased in people who smoke cannabis,” he told Healthline. “People are exposed to levels much higher than what one would be exposed to in a heavily polluted city, for example.”

Earlier research has also found that inhaling cannabis increases the level of carbon monoxide and tar in the bloodstream. Carbon monoxide intoxication is linked to problems such as irregular heart rhythm and heart failure.

Tetrahydrocannabinol (THC), the principal active compound in cannabis can also increase heart rate and blood pressure and affect other aspects of heart function.

Wold was pleased that one of the new studies focused on cannabis use among older adults, a group that has been understudied.

While some may think cannabis is mainly popular among young adults or middle-aged adults, “a lot of older adults are using cannabis products to treat lifelong or reoccurring health issues,” he said.

A 2020 study published in JAMA Internal Medicine found that cannabis use — including smoked or vaped cannabis and edibles — among Americans age 65 or older increased sharply from 0.4% in 2006 and 2007 to 2.9% in 2015 and 2016.

In addition, “as we get older, chronic conditions that contribute to cardiovascular disease are more prevalent,” Wold said. “So I think we’re finally getting more robust data on the direct effects of cannabis use on cardiovascular health in this population.”

The AHA Scientific Sessions study in older adults included over 28,000 people 65 years or older with cannabis use disorder and cardiovascular risk factors such as high blood pressure, type 2 diabetes or high cholesterol. Data came from a large nationwide database of hospitalizations.

An estimated three in 10 cannabis users have cannabis use disorder, according to the Centers for Disease Control and Prevention. People with this condition are unable to stop using cannabis even when it causes health problems or other negative effects in their lives.

In the new study researchers compared cannabis users to more than 10 million older adults with the same risk factors who didn’t use cannabis.

They excluded older adults who use tobacco, which in itself increases the risk of heart attack and stroke.

“What is unique about our study is that patients who were using tobacco were excluded because cannabis and tobacco are sometimes used together; therefore, we were able to specifically examine cannabis use and cardiovascular outcomes,” Dr. Avilash Mondal, a resident physician at Nazareth Hospital in Philadelphia, said in a news release.

Researchers found that 20% of older cannabis users with a risk factor for cardiovascular disease had an increased chance of having a major heart- or brain-related event while hospitalized, compared to non-cannabis users.

In addition, cannabis users had a higher rate of heart attacks, and were more likely to be transferred to other facilities, compared to people who didn’t use cannabis.

Researchers also found that having high blood pressure — over 130/80 millimeters mercury (mmHG) and high cholesterol — predicted major heart- and brain-related events in cannabis users.

High blood pressure, high cholesterol and tobacco smoking are three key risk factors for heart disease in all age groups.

The second study from the AHA meeting included more than 150,000 American adults, with an average age of 54, who participated in a research program sponsored by the National Institutes of Health. None of the participants had heart failure when they enrolled in the program.

Heart failure doesn’t mean the heart has stopped working, but that the heart no longer pumps as well as it should.

After nearly 4 years, daily cannabis users had a 34% increased risk of developing heart failure, compared to non-cannabis users. This risk was the same regardless of a person’s age, sex at birth and smoking history.

In the study, cannabis use was defined as using cannabis when not prescribed for a health condition; or if a person was prescribed medicinal cannabis, using it for another purpose.

When researchers took into account whether people had coronary artery disease, one of the most common types of heart disease, the risk of heart failure among cannabis users dropped to 27%. This suggests that coronary artery disease is a pathway through which daily marijuana use may lead to heart failure.

One limitation of both studies is that they didn’t identify which types of cannabis products people used. It is possible that the heart- and brain-related risks of cannabis are different for smoked or vaped products versus edibles. More research is needed.

In addition, the majority of participants were white. Cannabis use is higher among people who are Black, compared to those who are white, Hispanic, or Latino, according to a 2021 report from the Substance Abuse and Mental Health Services Administration (SAMHSA).

So “future studies need to have a much more diverse sample compared to what’s what’s included here,” said Wold.

Both studies are also observational, so they may not have taken into account all factors that could affect a person’s risk of heart attack, stroke and heart failure.

“The studies do not allow us to separate the contributions of other associated behaviors that accompany recreational marijuana use,” said Hirsh. “These include lack of exercise, poor nutritional decisions, lack of sleep and lack of prioritizing health in general.”

However “it is very likely that the use of inhaled marijuana can be harmful to our coronary arteries and heart muscle,” he said.

Two preliminary studies presented at an American Heart Association scientific meeting found that cannabis users had a higher risk of heart attack, heart failure and stroke, compared to non-cannabis users.

In one study, older adults with cannabis use disorder and risk factors for cardiovascular disease had a higher risk of a major heart- or brain-related event while hospitalized, compared to people who don’t use cannabis.

In a second study, daily cannabis users had an increased risk of developing heart failure after nearly four years, compared to non-cannabis users.