Weed smoking or vaping can trigger heart attacks and strokes, says American Heart Association
Marijuana is not good for the heart and has the potential to trigger cardiovascular events such as heart attacks and strokes, as well as interfere with prescribed medications, according to a scientific statement issued by the American Heart Association (AHA).
The US medical body says that the chemicals in cannabis or marijuana have been linked to an increased risk of heart attacks, heart failure and atrial fibrillation in observational studies, but a full understanding of how the use of cannabis affects the heart and blood vessels is limited by a lack of adequate research. The authors explain that while cannabis may be helpful for conditions such as spasticity associated with multiple sclerosis, among others, it does not appear to have any well-documented benefits for the prevention or treatment of cardiovascular diseases. Preliminary studies have found that cannabis use could negatively impact the heart and blood vessels, they warn.
“Attitudes towards recreational and medicinal use of cannabis have changed rapidly, and many states have legalized it for medical and/or recreational use. Healthcare professionals need a greater understanding of the health implications of cannabis, which has the potential to interfere with prescribed medications and/or trigger cardiovascular conditions or events, such as heart attacks and strokes,” says Robert L Page II, chair of the writing group for the statement and professor in the department of clinical pharmacy and the department of physical medicine/rehabilitation at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado.
According to health experts, besides the poisonous compounds in cannabis smoke, vaping cannabis may also result in serious health outcomes, especially when it is mixed with vitamin E acetate oils, which are linked to EVALI (e-cigarette or vaping product use-associated lung injury), the potentially fatal illness that emerged among e-cigarette users last year.
“People who use cannabis need to know there are potentially serious health risks in smoking or vaping it, just like tobacco smoke. 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,” writes Dr Rose Marie Robertson, the deputy chief science and medical officer for the AHA and co-director of the AHA Tobacco Center for Regulatory Science, in the statement published in the AHA journal Circulation.
The findings
The authors write that the most common chemicals in cannabis include THC (tetrahydrocannabinol), the component of the plant that induces a ‘high’ and CBD (cannabidiol), which can be purchased over the counter. However, to date, the FDA has only approved one CBD-derived product. The FDA has not approved any other cannabis, cannabis-derived, or cannabidiol (CBD) products currently available on the market, they emphasize.
A recent study cited in the statement suggests that cannabis use is present in 6% of heart attack patients under the age of 50. Another study found that cannabis users in the 18 to 44 age group had a significantly higher risk of having a stroke compared to non-users. “Unfortunately, most of the available data are short-term, observational and retrospective studies, which identify trends but do not prove cause and effect,” explains Page.
Some studies have found that within an hour after cannabis is smoked, THC may induce heart rhythm abnormalities, such as tachycardia, premature ventricular contractions, atrial fibrillation, and ventricular arrhythmias. “Acutely, THC also appears to stimulate the sympathetic nervous system, which is responsible for the ‘fight or flight’ response, resulting in a higher heart rate, a greater demand for oxygen by the heart, higher blood pressure while laying down and dysfunction within the walls of the arteries,” reveals analysis. In contrast, studies on CBD, which do not produce a high or intoxication, have found associations with reduced heart rate, lower blood pressure, increased vasodilation (the ability of the arteries to open), lower blood pressure and potentially reduced inflammation. Inflammation is linked to atherosclerosis, the slow narrowing of the arteries that underlies most heart attacks and, possibly strokes.
Smoking and inhaling cannabis, regardless of THC content, has been associated with cardiomyopathy (heart muscle dysfunction), angina (chest pain), heart attacks, heart rhythm disturbances, sudden cardiac death, and other serious cardiovascular conditions. In states where cannabis has been legalized, an increase in hospitalizations and emergency department visits for heart attacks has been observed, explain researchers.
The way cannabis is consumed may influence how it affects the heart and blood vessels. “Many consumers and health care professionals don’t realize that cannabis smoke contains components similar to tobacco smoke,” says Page. Smoking and inhaling cannabis, regardless of THC content, has been shown to increase the concentrations of blood carboxyhemoglobin (formed from carbon monoxide, a poisonous gas) five-fold, and a three-fold increase in tar (partly burnt combustible matter), similar to the effects of inhaling a tobacco cigarette.
According to the researchers, carbon monoxide intoxication from inhaled tobacco or cannabis has been associated with several heart problems such as heart muscle disease, chest pain, heart attacks, heart rhythm disturbances, and other serious conditions.
The statement also discusses cannabis use among older adults, people diagnosed with cardiovascular diseases, and other populations including youth. Some studies have suggested that cannabis use — both CBD and THC — may be safe and effective for older populations. Though they are the least likely to use cannabis, older adults often use it to reduce neuropathic pain (common among people with type 2 diabetes), improve quality of life, and decrease prescription drug use (including opioids). Additionally, benefits for patients with age-related diseases, including Parkinson’s and Alzheimer’s, have also been reported in some studies. But there is very little research on the long-term effects of cannabis use among this group of people, caution experts.
Another concern about older adults using cannabis is the potential of interactions with other medications, including blood thinners, anti-depressants, antipsychotics, antiarrhythmics for heart rhythm abnormalities, and statin drugs, which reduce cholesterol levels, the statement argues. “For people diagnosed with heart disease, cannabis should be used with extreme caution because cannabis increases the heart's need for oxygen at the same time as it decreases available oxygen supply, which could cause chest pain. Besides, in some studies, cannabis triggered a heart attack in people with underlying heart disease. Other studies have linked cannabis use to a higher risk of strokes and heart failure,” reads the statement.
What’s the way forward?
The AHA recommends that cannabis use should be discussed in detail with a healthcare professional so that a person's potential health risks can be reviewed. “If people choose to use cannabis for its medicinal or recreational effects, the oral and topical forms, for which doses can be measured, may reduce some of the potential harms. It is also vitally important that people only use legal cannabis products because there are no controls on the quality or the contents of cannabis products sold on the street,” explains Page.
The report highlights the need for all clinicians to have greater exposure to and education on the various cannabis products and their health implications during their initial training and continuing education. They must be “alert to the possibility that the use of cannabis or its potent synthetic analogs” might be the underlying cause of severe cardiovascular events and pathologies, it adds.
The experts have also called for more studies into the effects of cannabis on the heart and blood vessels. Research on the same has been limited because cannabis is categorized as a Schedule I controlled substance by the US Drug Enforcement Agency (DEA). Schedule I controlled substances are defined as having no accepted medical use, a high potential for abuse, and an unacceptable safety profile.
The scientific statement suggests that the DEA remove cannabis from the Schedule I of the US Controlled Substances Act so that it can be widely studied by scientists. Currently, 47 US states, the District of Columbia, and four out of five US territories allow some form of cannabis use, and its use has risen considerably over the past decade, particularly among people 18-25 years of age. The team says that while many states have legalized medical and/or recreational cannabis use, cannabis growing, sales, and use are illegal at the federal level, further complicating scientific research.
The AHA recommends that funding must be increased proportionally to match the expansion of cannabis use. “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. 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,” says Page.