In a new scientific statement, researchers say the chemicals in cannabis have been linked to an increased risk of heart attacks, heart failure, and atrial fibrillation in observational studies.
However, a full understanding of how the use of cannabis affects the heart and blood vessels is limited by a lack of adequate research.
The research was conducted by a team at the American Heart Association (AHA).
According to the statement, although cannabis, also known as marijuana, may be helpful for conditions such as spasticity associated with multiple sclerosis, among others, cannabis 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.
A recent study cited in the statement suggests that cannabis use is present in 6% of heart attack patients under 50 years of age.
Another study found that cannabis users ages 18 to 44 had a significantly higher risk of having a stroke compared to non-users.
The team says most of the available data are short-term, observational, and retrospective studies, which identify trends but do not prove cause and effect.
The most common chemicals in cannabis include THC (tetrahydrocannabinolic acid), the component of the plant that induces a “high,” and CBD (cannabidiol), which can be purchased over the counter, but to date, the FDA has only approved one CBD-derived product.
Importantly, the FDA has not approved any other cannabis, cannabis-derived, or cannabidiol (CBD) products currently available on the market.
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.
In contrast, studies on CBD, which does not produce a “high” or intoxication, have found associations with reduced heart rate, lower blood pressure, increased vasodilation (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.
The way cannabis is consumed may influence how it affects the heart and blood vessels.
Smoking and inhaling cannabis, regardless of THC content, has been shown to increase the concentrations of blood carboxyhemoglobin (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.
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.
Cannabis use should be discussed in detail with a health care professional so that an individual’s potential health risks can be reviewed.
In addition to 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.
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; however, there is very little research on the long-term effects of cannabis use among this group of people.
Another concern about older adults using cannabis is the potential of interactions with other medications, including blood thinners (anti- coagulants), anti-depressants, antipsychotics, antiarrhythmics for heart rhythm abnormalities, and statin drugs, which reduce cholesterol levels.
The team says 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 angina (chest pain).
In addition, 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.
One author of the study is Robert L. Page II, Pharm.D., M.S.P.H., FAHA.
The study is published in Circulation.
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