According to findings from two preliminary studies presented at the American Heart Association’s Scientific Sessions 2023, after taking into account other risk factors for cardiovascular disease such as type 2 diabetes, hypertension, and obesity, routine use of marijuana may augment the risk of heart failure, stroke, or myocardial infarction.

While the effects of marijuana on heart and brain health are not entirely known, the findings from the two recent studies conducted by separate research groups highlight the impact of regular use of marijuana on increased risk of HF, myocardial infarction, and stroke.

In the study titled Daily Marijuana Use is Associated with Incident Heart Failure: “All of Us” Research Program, scientists concentrated on the correlation between lifestyle, biology, and environment in diverse populations and investigated the relationship between daily marijuana use and HF.

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

Dr. Bene-Alhasan and colleagues followed 156,999 individuals who did not have HF when they enrolled in the research program. Study participants completed a survey about the frequency of their use of marijuana and were monitored for approximately 4 years (45 months). The analysis was modified to account for individual demographic and economic factors, alcohol use, smoking, and other cardiovascular risk factors associated with HF, such as type 2 diabetes, hypertension, hyperlipidemia, and obesity. For this study, the definition of marijuana use was “using marijuana when not prescribed for a health condition, or, if prescribed for medical purposes, using it outside that purpose.”

Study findings revealed the following:

• During the study period, 2,958 individuals (almost 2%) developed HF
• Individuals who reported daily marijuana use had a 34% augmented risk of developing HF compared with those who reported never using marijuana. This risk was the equivalent regardless of age, gender, or smoking history
• In a secondary analysis, when coronary artery disease was added to the review, the risk of HF declined from 34% to 27%, suggesting that coronary artery disease is a route through which daily marijuana use may result in HF.

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

The researchers noted, “A limitation of the study is that it relied on data that did not specify whether the marijuana was inhaled or eaten. According to researchers, how marijuana is ingested may influence cardiovascular outcomes.”

In a second study titled Increased Risk of Major Adverse Cardiac and Cerebrovascular Events in Elderly Non-Smokers Who Use Cannabis, other researchers assessed data from the 2019 National Inpatient Sample, the largest nationwide database of hospitalizations, to examine whether hospital stays among patients who used marijuana were complicated by a cardiovascular event, including myocardial infarction, stroke, cardiac arrest, or arrhythmia.

For this study, the researchers obtained records on adults aged older than 65 years with cardiovascular risk factors who reported no tobacco use (cigarettes or other tobacco products). This group of patient records was then separated into two groups: marijuana users and non–marijuana users. The marijuana users’ hospital records were coded for cannabis-use disorder, which can vary from hospital to hospital.

Lead study author Avilash Mondal, MD, a resident physician at Nazareth Hospital in Philadelphia, stated, “Since 2015, cannabis use in the U.S. has almost doubled, and it is increasing in older adults, therefore, understanding the potential increased cardiovascular risk from cannabis use is important. 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.”

The study contained 28,535 cannabis users with existing cardiovascular risk factors (hypertension, type 2 diabetes, or hyperlipidemia). The comparison group included 10,680,000 adults with the same risk factors who did not use marijuana, and the findings revealed:

• 20% had an augmented risk of having a major heart or brain event while hospitalized, compared with the group who did not use cannabis
• 13.9% of cannabis users with cardiovascular risk factors had a major adverse heart and brain event while hospitalized compared with non–cannabis users
• Additionally, the cannabis users, in comparison with non–cannabis users, had a greater rate of myocardial infarction (7.6% vs. 6%, respectively) and were more likely to be transferred to other facilities (28.9% vs. 19%)
• Hypertension (defined as greater than 130/80 mmHg) and hyperlipidemia were predictors of major adverse heart and brain events in marijuana users.

Dr. Modal stated, “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. Healthcare professionals should include the question, ‘Are you using cannabis?’ when taking a patient’s history. If you ask patients if they are smoking, people think cigarette smoking. 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.”

The presenters noted, “A limitation of the analysis is that the data is from a large database, which may have coding errors in the patients’ health records. In addition, the electronic health record code for cannabis use disorder may vary from hospital to hospital, thereby skewing the results of the analysis.”

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