Marijuana use increases risk of heart attacks, new studies suggest

Two new studies suggest that regular use of marijuana could be linked to a higher risk of heart failure or heart attack, especially among older people. 

The preliminary findings of the studies, which have yet to be published, will be presented next week at the American Heart Association’s (AHA) Scientific Sessions 2023 in Philadelphia.

The first study followed 156,999 people for 45 months, nearly four years. At the start of the study, all participants were free from heart failure and filled out a survey about their marijuana use, which was defined as “using marijuana when not prescribed for a health condition, or, if prescribed for medical purposes, using it beyond that purpose.” 

The study found that those who used marijuana daily had a 34 percent increased risk of developing heart failure, when compared with those who said they never used marijuana. Throughout the study, nearly 2 percent — 2,958 people — developed heart failure.

When accounting for coronary artery disease, however, the risk dropped from 34 percent to 27 percent, which researchers said could reveal that “coronary artery disease is a pathway through which daily marijuana use may lead to heart failure.”

The press release noted that research did not specify whether the marijuana was eaten or inhaled, which “may influence cardiovascular outcomes,” research said.

“Prior research shows links between marijuana use and cardiovascular disease like coronary artery disease, heart failure and atrial fibrillation, which is known to cause heart failure,” lead study author Yakubu Bene-Alhasan, a resident physician at Medstar Health in Baltimore, said in the press release. “Marijuana use isn’t without its health concerns, and our study provides more data linking its use to cardiovascular conditions.”

“Our results should encourage more researchers to study the use of marijuana to better understand its health implications, especially on cardiovascular risk,” Bene-Alhasan added. “We want to provide the population with high-quality information on marijuana use and to help inform policy decisions at the state level, to educate patients and to guide health care professionals.”

A second study analyzed data from the 2019 National Inpatient Sample, which the press release described as the largest database of hospitalizations. The researchers pulled data on adults ages 65 and older with cardiovascular risk factors. They focused on those who reported no tobacco use, and then divided the patient records into two groups: marijuana users and nonusers. 

The study, which looked at 28,535 marijuana users, found that marijuana users had a 20 percent increased chance of “having a major heart or brain event while hospitalized,” compared with the other group. Nearly 14 percent of marijuana users “had a major adverse heart and brain event while hospitalized compared to non-cannabis users.” 

Researchers warned that more data is needed to determine the risk of marijuana usage. They encouraged health professionals to ask about marijuana specifically, not just smoking, when taking a patient’s medical history.  

“We must be mindful about major heart and stroke events in older adults with cannabis use disorder,” lead study author Avilash Mondal, a resident physician at Nazareth Hospital in Philadelphia, said in the press release.

“The main public message is to be more aware of the increased risks and open the lines of communication so that cannabis use is acknowledged and considered,” Mondal added.