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Two separate studies suggest that long-term cannabis use could lead to a serious cardiovascular event. Daniel Brothers/Getty Images
  • Two separate studies examined the long-term use of cannabis and the impact it may have on the heart.
  • The first study showed that daily cannabis use increases the risk of developing heart failure by 34%.
  • The second study found that older cannabis users are more likely to have a heart attack or other heart event during hospital stays.
  • Though the findings are compelling, they are limited since the studies didn’t examine whether people inhaled cannabis or consumed edibles.
  • The scientists hope that continuing research in this area will help cannabis users become better informed and help healthcare providers be better informed about how to guide their patients.

The National Institutes of Health (NIH) reports that cannabis use increased by approximately 50% over the past decade. In a survey conducted in 2022, the number of people who reported using cannabis over the prior year was 44%, an increase from 28% in 2012.

Part of the reason for this is the legalization of cannabis, either for recreational use or medicinal use in several states.

While there is an abundance of research on the benefits cannabis use may have for alleviating anxiety symptoms, reducing pain levels, and helping stomach conditions, some scientists have concerns over whether regular cannabis use can adversely impact health.

In two studies, researchers took a close look at how cannabis use can impact the heart over time. One of the studies follows participants and their cannabis use over a 4-year period, and the other study evaluated data from the 2019 National Inpatient Sample.

The researchers will present their findings at the American Heart Association’s Scientific Sessions 2023 conference.

Dr. Yakubu Bene-Alhasan, a physician at MedStar Health in Baltimore, led one of the cannabis studies and focused on cannabis use and heart failure.

“With the increasing state-level legalization of marijuana across the United States, its use has increased exponentially, especially among the youth,” Dr. Bene-Alhasan noted in the research abstract. “However, a lot remains unknown concerning its cardiovascular health implications.”

This study utilized data from nearly 157,000 people who participated in the All of Us Research Program.

The researchers followed the participants for 4 years. When the study began, none of the participants had heart failure, and they provided information about how often they used cannabis (the researchers did not ask whether the participants ingested or inhaled cannabis).

Some of the participants reported using cannabis recreationally, while others had a prescription for it. For the latter group, the researchers were interested in their cannabis use beyond what their providers prescribed.

By the end of the study, around 2% of the participants developed heart failure, and people who used cannabis daily had a 34% higher risk of developing heart failure.

“Our results should encourage more researchers to study the use of marijuana to better understand its health implications, especially on cardiovascular risk,” said Dr. Bene-Alhasan.

While daily cannabis use impacted heart failure, Dr. Bene-Alhasan told Medical News Today that occasional use was not linked to heart failure.

“Daily use was associated with an increased risk of heart failure,” said Dr. Bene-Alhasan. “Less frequent use was not associated with an increased risk of heart failure or found to be protective.”

The second study focused on cannabis use in adults over the age of 65.

Dr. Avilash Mondal, a physician at Nazareth Hospital in Philadelphia, led this study. Dr. Mondal reported that cannabis use has doubled in older adults in recent years, making it important to evaluate the impact it may have on heart disease in this age bracket.

The focus of Dr. Mondal’s study was to determine whether cannabis use can impact hospital stays in people who are at a higher risk for heart events. After excluding tobacco users, the researchers compared data from cannabis users and non-users.

The scientists had access to data from 28,535 cannabis users, and they focused on whether these people experienced more cardiovascular events during their hospital stays than people with no cannabis use.

The results were staggering — cannabis users were 20% more likely to experience a cardiovascular event or a stroke during their hospital stays.

According to the study abstract, almost 14% of people who reported cannabis use had major adverse cardiac and cerebrovascular events during their hospital stays.

Cannabis users also had higher rates of strokes, arrhythmogenic cardiomyopathy, and acute myocardial infarctions.

Dr. Mondal said the study results emphasize the importance of providers checking in with their patients about cannabis use.

“We must be mindful about major heart and stroke events in older adults with cannabis use disorder. At this point, we need more studies to understand the long-term effects of cannabis use,” said Dr. Mondal.

Dr. Richard Wright, a board certified cardiologist at Providence Saint John’s Health Center in Santa Monica, California, also spoke with MNT about the study.

“These provocative findings could be significant in view of the increasing use of cannabis and the perhaps naïve belief that the drug is safe,” said Dr. Wright.

Dr. Wright pointed out a weakness in the study, noting that it did not evaluate whether participants inhaled or ingested cannabis.

“This is a critical issue, as any inhaled combustible material contains noxious substances which are known to have potential pulmonary, cardiovascular, and systemic adverse effects,” commented Dr. Wright.

Dr. Wright also noted that people who use cannabis daily may be using it for chronic pain conditions, putting them at a higher risk for heart failure.

Dr. Cheng-Han Chen, a board certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, California, also weighed in on the study.

Dr. Chen noted that the study adds to growing research showing cannabis use can negatively impact the heart. “It is only in the last few years that researchers have gathered data associating cannabis use to worsened clinical cardiovascular outcomes,” said Dr. Chen.

Dr. Chen also commented on the possible effects of ingested versus inhaled cannabis:

“It is thought that ingesting THC increases systolic absorption of the chemical when compared to smoking THC, and thus results in greater adverse effects. However, cannabis smoke comes with a separate set of health concerns, as the smoke contains many carcinogens and mutagens similar to tobacco smoke.”

According to the Centers for Disease Control and Prevention (CDC), 3 out of 10 cannabis users have cannabis use disorder (CUD).

The CDC notes that these users “are unable to stop using marijuana even though it’s causing health and social problems in their lives.”

Some symptoms of cannabis use disorder include:

  • regularly craving cannabis
  • increasing cannabis use to get high
  • going through withdrawal when trying to stop using cannabis
  • experiencing social problems as a result of cannabis use

People who have concerns about cannabis use disorder should talk with their healthcare providers or contact the Substance Abuse and Mental Health Services Administration (SAMHSA) hotline for advice.