- THC is the most important mind-altering (psychoactive) ingredient in cannabis, like marijuana, that can cause a person to feel high.
- THC-containing products stimulate the heart and promote vascular inflammation and oxidative stress.
- This can lead to increased blood pressure, abnormal heart rhythms, and an overall higher risk of heart attack, stroke, and sudden death.
Cannabis can have medicinal properties, but it can also be harmful to the heart and blood vessels, according to a report by the American Heart Association (AHA).
The AHA statement in the journal Circulation looked at several studies on the subject, as cannabis use has increased in recent decades.
Cannabis, also called marijuana, refers to the varieties of cannabis plants that contain tetrahydrocannabinol (THC).
THC is the most important mind-altering (psychoactive) ingredient in cannabis that can make a person feel high. Cannabinoids are compounds found in cannabis. Cannabidoil or CBD is a commonly known cannabinoid that has some health benefits. CBD is different from THC.
Researchers have found it difficult to study cannabis because it is listed by the FS Controlled Substances Act as a Scheme 1 controlled substance. By definition, this means that it has no medical use and is likely to be abused. In the report, the AHA urged the federal drug insurance administration to remove it from the designation.
Chemicals in cannabis have been linked to higher risk of heart attack, heartbeat, and atrial fibrillation. But those studies are observational and did not prove that the chemicals were the cause of the increased risk.
One study cited in the AHA statement reported that 6 percent of patients under the age of 50 who had a heart attack used cannabis. It was linked to worse all-cause and cardiovascular mortality. Another study found a significantly higher chance of a stroke among cannabis users aged 18 to 44, with even greater chances in those who consumed it more often compared to those who did not use cannabis.
Dr. Chip Lavie, a cardiologist at the Ochsner Medical Center in New Orleans, Louisiana, said it is already known that cannabis can have negative effects on coagulation, increase acute cardiovascular events, and lead to poor vascular effects.
“We still have no idea about the impact on casual users, high-dose users, and very chronic users,” Lavie told Healthline.
If cannabis is used in the short term in some patients, the benefits may outweigh the risks. Additional dangers with unclean products and vaping still exist, though, he noted.
Dr. Muthiah Vaduganathan, a cardiologist at Brigham and Women’s Hospital in Boston, Massachusetts, pointed out that certain forms of cannabis delivery, such as vaping, can have unique implications for cardiovascular health.
Because cannabinoid receptors are distributed throughout the body, including in the heart, there is a potential for effects on the heart, Vaduganathan said.
Not all cannabis research shows harm, the AHA report stated.
THC-containing products stimulate the heart and promote vascular inflammation and oxidative stress. This can lead to high blood pressure, abnormal heart rhythms, and an overall higher risk of heart attack, stroke, and sudden death, explained Dr. Michael Miller, a professor of cardiology at the University of Maryland School of Medicine.
If THC concentrations are too high, or taken in a short time, there is a potential for adverse reactions, such as in older people on existing medications.
In contrast, CBD-containing products reduce inflammation and emotional stress which in turn can serve to reduce the risk of heart disease.
“I was unaware of the potential adverse effects between THC in promoting heart disease compared to CBD that may protect against its development and progression,” Miller notes.
Although cannabis may be an effective treatment for medical purposes, such as controlling infection, or reducing nausea and improving appetite in people with cancer such as HIV, some people are unaware of its potential harm when used for recreational or nonproven purposes, said Miller.
Miller hopes to conduct a well-designed clinical trial to determine whether daily use of CBD reduces the risk of heart attack, stroke or cardiovascular death.
Experts note a lack of robust data when specifying the harm and benefits of cannabis on the cardiovascular system. Because of increasing concentrations of THC in cannabis, previous studies can only reflect the implications of lower levels of THC in humans, the AHA report stated.
Most cannabis studies are observational and do not take into account that some cannabis users also smoke cigarettes, Miller added.
“I would like to know if, and to what extent, THC can be harmful to the heart in the absence of important risk factors, such as cigarette smoke,” he added.
Dr Stephen Sidney, a senior research scientist with the Kaiser Permanente Northern California Division of Research in Oakland, California, said more research is urgent because more people 65 and older are using cannabis – and they are at the highest risk for heart attacks.
“Most of what we know about the cardiovascular effects of marijuana comes from studies of smoked marijuana. Much more research needs to be done into other forms of marijuana, such as edible things, tinctures, and preparations, ”Sidney told Healthline. “We also need to investigate how smoking marijuana affects the heart and lungs, as this has taken over the smoking of marijuana cigarettes as the most common use by teens.”
Patients and physicians need to be open about cannabis use and implications, Vaduganathan said.
“While cardiologists often ask and advise patients about tobacco use, they rarely look at cannabis use. “Patients may not recognize that cannabis can have significant effects on blood pressure, cardiovascular metabolism, and overall heart health – some of which may actually be very similar to the negative health effects of tobacco smoke,” Vaduganathan said.
Some forms of cannabis use are permitted in 47 states, the District of Columbia, and 4 of 5 U.S. territories. Selling and using is still illegal federally, although varying procurement and use practices are legal in many states.
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