Cannabis Use May Risk Cardiovascular Health, Says American Heart Association

While cannabis may have useful applications in some areas of medicine, such as controlling epileptic seizures, the same perhaps cannot be said for cardiovascular health.

A new scientific statement from the American Heart Foundation has warned that cannabis use does not seem to confer any particular benefits to heart health, with some studies even showing that cannabis use may be linked to an increased risk of heart attacks, atrial fibrillation, and heart failure.

“People who use cannabis need to know there are potentially serious health risks in smoking or vaping it, just like tobacco smoke,” said Rose Marie Robertson, the deputy chief science and medical officer for the American Heart Association and co-director of the AHA Tobacco Center for Regulatory Science, in an accompanying news release.

“The American Heart Association recommends that people not smoke or vape any substance, including cannabis products, because of the potential harm to the heart, lungs, and blood vessels.”

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The scientific statement, published in the AHA’s flagship journal Circulation, reviews a number of existing observational scientific studies on cannabis and heart health. The AHA authors found cannabis to have no well-documented benefits for the prevention or treatment of cardiovascular conditions. They also presented a number of preliminary studies suggesting that cannabis may actually negatively impact the heart and blood vessels.

One study referenced in the statement found that cannabis use is reported by 6 percent of those aged 50 or under who have experienced heart attacks. A recent paper published in the Journal of the American College of Cardiology calculated that an estimated 2 million cannabis consumers are currently living with some type of cardiovascular disease.

“We do acknowledge the limited scope of evidence defining the cardiovascular safety of marijuana at present,” Muthiah Vaduganathan, a co-author of the JACC paper and cardiologist at Brigham, told Analytical Cannabis following the study’s publication. “However, based on what we know, we believe there is sufficient evidence to give us pause.”

Another study highlighted in the scientific statement found that cannabis users between the ages of 18 and 44 are at a significantly higher risk of having a stroke than their non-cannabis using peers.

“Unfortunately, most of the available data are short-term, observational and retrospective studies, which identify trends but do not prove cause and effect,” said Robert Page II, who chaired the writing group for the statement and is a professor at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences.

Several studies focused solely on the effects of individual cannabinoids and their methods of consumption. Consumption of THC, the predominant intoxicant in cannabis, was found to induce a heart rhythm abnormalities, such as tachycardia and premature ventricular contractions, within an hour of smoking cannabis.

Acute THC consumption was found to stimulate the body’s “fight or flight” response, causing an increase in heart rate and a greater demand for oxygen by the heart, resulting in higher blood pressure while laying down and dysfunction within the walls of the arteries. Conversely, CBD was linked to reduced heart rate, lower blood pressure, and potentially also a reduction in inflammation.

Regardless of the CBD or THC content of the cannabis in question, the AHA warns that smoking cannabis can increase the concentrations of blood carboxyhemoglobin (a complex formed between hemoglobin and harmful carbon monoxide) and tar in the lungs.

“Many consumers and health care professionals don’t realize that cannabis smoke contains components similar to tobacco smoke,” said Page.

Smoking cannabis or tobacco can produce amounts of carbon monoxide. As the statement explains, inhaling this can potentially lead to heart muscle disease, chest pain, heart attacks, heart rhythm disturbances, and other serious conditions.

The need for further research

The AHA recognizes that due to the rapidly shifting landscape of cannabis laws, there is an even greater need for scientifically-informed policy. However, under the current suite of federal restrictions, conducting the necessary research is extremely challenging.

The scientific statement suggests several policy recommendations and future directions for consideration. Firstly, the AHA scientists ask for the removal of cannabis from Schedule 1 of the US Controlled Substances Act, followed by reform of current labeling practices in order to standardize concentrations of THC and CBD content.

Researchers’ access to Schedule 1 drugs is tightly restricted, and this can create significant barriers to research. For example, the process of receiving necessary approvals from the Food and Drug Administration (FDA) and the Drug Enforcement Administration (DEA) for cannabis research projects can easily take a whole year. The rescheduling of cannabis could provide immediate relief from tight restrictions such as this.

The AHA also asks that cannabis should be integrated into exists tobacco control and prevention efforts. Specifically, the association names age restrictions on purchasing, retailer compliance, excise taxes, comprehensive smoke-free air laws, professional education, screening within the clinical environment, and the coverage of cessation treatment programs by insurers as key areas for improvement. Additionally, they suggest that a portion of the money raised from cannabis taxes be put towards funding public health services and initiatives.

“We urgently need carefully designed, prospective short- and long-term studies regarding cannabis use and cardiovascular safety as it becomes increasingly available and more widely used,” Page said.

“The public needs fact-based, valid scientific information about cannabis’ effect on the heart and blood vessels. Research funding at federal and state levels must be increased to match the expansion of cannabis use – to clarify the potential therapeutic properties and to help us better understand the cardiovascular and public health implications of frequent cannabis use.”