Will smoking cannabis harm your heart?, yes says AMA

By Dr. Ananya Mandal, MDAug 6 2020

The American Heart Association (AHA), in their statement, has said that smoking cannabis (marijuana) could be harmful to the heart. This new stand on smoking weed was published this week in the journal Circulation. The announcement is released as an article titled, “Medical Marijuana, Recreational Cannabis, and Cardiovascular Health: A Scientific Statement From the American Heart Association.”

The statement from Dr. Rose Marie Robertson, the deputy chief science and medical officer for the American Heart Association, was, “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.” This statement piece was approved by the American Heart Association Science Advisory and Coordinating Committee on May 18, 2020, followed by the American Heart Association Executive Committee on June 22, 2020.

AMA Statement: Medical Marijuana, Recreational Cannabis, and Cardiovascular Health: A Scientific Statement From the American Heart Association. Image Credit: guruXOX / Shutterstock

Cannabis in therapy

Cannabis or marijuana has been approved for medicinal use in several regions in the United States. The authors of the new report write that it has the potential to provide benefits in several conditions. Key components of cannabis that provide medicinal benefits are “Δ-9-tetrahydrocannabinol and cannabidiol,” they wrote.

Over the past nearly three decades, the stance towards cannabis has undergone a sea change, they wrote. There has been gradual legalization of both medical and recreational use of the drug in the USA, Canada, and Uruguay.

Use of cannabis and its safety

With the gradual legalization of cannabis and its acceptance in medicinal use, there is a considerable rise in the use of cannabis among the youth, especially. The authors of the report state that over the past decades, there has been illegal use of this drug, and thus its safety and efficacy have been challenging to study. There is little concrete evidence proving its safety. At present, in the USA, it is classified as a Schedule 1 controlled substance. They wrote, “These shifts in cannabis use require clinicians to understand conflicting laws, health implications, and therapeutic possibilities.”

Cannabis and the heart

The team of researchers said that there might be health benefits of cannabis in certain disease conditions, and it may play a role in pain management. However, there is no proven benefit of cannabis on the cardiovascular system. They write, “...many of the concerning health implications of cannabis include cardiovascular diseases”. The team, however, adds that the route of administration of the drug (smoked or other) may determine the actual level of harm it may cause to the cardiovascular system.

Clinical pharmacologist Robert Page II, who chaired the team that wrote the statement, said that cannabis has “the potential to interfere with prescribed medications” and also “trigger cardiovascular conditions or events, such as heart attacks and strokes.” Dr. Page, a professor in the department of clinical pharmacy and physical medicine/rehabilitation at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado, warned that those using marijuana need to discuss these issues with their health care professional.

Route of use

The statement said that the method administration of the drug could play a role in its risks to the cardiovascular system. Dr. Page explained, “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.” Topical forms are preparations that could be applied over the skin or mucous membranes. He added, “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.”

Typical heart conditions are seen with cannabis use

The statement critically reviewed the evidence that showed that common heart conditions associated with cannabis use. They write that heart rhythm problems are one of the most prevalent associated problems with cannabis use. These include tachycardia, atrial fibrillation, which can be seen within one hour of cannabis use. Typically weed containing THC or tetrahydrocannabinol when smoked causes these heart rhythm problems. THC is the primary psychoactive component of marijuana that causes the “high.” It can raise the requirement of oxygen of the heart and raise blood pressure among those who are susceptible, the experts say.

The statement went on to say that some individuals may experience chest pain and even heart attacks, along with other heart problems that are commonly seen with both cannabis and tobacco use. Page said, “Cannabis smoke contains components similar to tobacco smoke.” He added that cannabis, when smoked just like tobacco smoke, raises carbon monoxide and tar consumption. Strokes, heart attacks, and heart failure risk thus go up among those using cannabis, the statement said.

The relatively harmless component of cannabis

CBD or cannabidiol present in cannabis, on the other hand, is not psychoactive and also does not harm the heart. Some studies have shown that CBD could reduce heart rate and blood pressure. It is also associated with less risk of inflammation, which is a direct contributor to atherosclerosis, strokes, and coronary artery disease.

Among the approved products, there is only one CBD-derived product that is available for sale online, and over the counter, they write. This product is US Food and Drug Administration (FDA) approved.

More research

Page said that there had been few long term studies looking at both safety and benefits of cannabis use. This is because the drug has long been in illegal use. Page said the available studies are all, “short-term, observational and retrospective studies, which identify trends but do not prove cause and effect.” He called for “carefully designed, prospective short- and long-term studies regarding cannabis use and cardiovascular safety.” “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,” he said.