People who use marijuana could be at increased risk for heart complications like heart attack and heart failure, according to new research presented by the American Heart Association (AHA) at its 2023 Scientific Sessions conference.

Marijuana use linked with increased risk of heart attack, heart failure. American Heart Association.

Page RL, Allen LA, Kloner RA, et al. Medical marijuana, recreational cannabis, and Cardiovascular Health: A Scientific Statement from the American Heart Association.Circulation. 2020;142(10).

 

 

In the research that was presented, studies linked regular marijuana use to stroke, heart attack, and heart failure, even when accounting for other coexisting cardiovascular risk factors like Type 2 diabetes, high blood pressure, and obesity.

Another study showed that for adults older than 65 with cardiovascular risk factors who did not use tobacco, cannabis (the medical term for marijuana) use can increase the risk of major adverse heart and brain events.

Marijuana use linked with increased risk of heart attack, heart failure. American Heart Association.

 

In the findings presented, researchers did not separate results based on method of use.

 

What makes marijuana risky?

 

More studies are needed to flesh out the reasons behind marijuana’s impact on the heart. Some researchers suggest that the method of use may affect risk levels, with smoking potentially being riskier than other methods.

In a 2020 statement, the AHA said that cannabis’s impact on cardiovascular health “may be mediated by mechanisms of delivery.” 

“Cannabis may have therapeutic benefits, but few are cardiovascular in nature,” the AHA wrote. “Conversely, many of the concerning health implications of cannabis include cardiovascular diseases…”

However, the studies did not separate for inhaled versus consumed marijuana.

Richard Wright, MD, a board-certified cardiologist at Providence Saint John’s Health Center in Santa Monica, CA, says that “the most important and glaring problem is that the studies did not discern whether daily marijuana use meant use of inhaled marijuana, or frequent ingestion of edible cannabis.”

“This is a critical issue, as any inhaled combustible material contains noxious substances, which are known to have potential pulmonary, cardiovascular, and systemic adverse effects,” Dr. Wright said.

On the other hand, consuming marijuana may subject people to a different set of health risks.

 

Tolerance and risk level 

 

It is also people’s tolerance for marijuana/cannabis that may impact their risk levels for cardiovascular complications, Dr. Wright says.

“In almost all circumstances, there is a dose-response relationship to intake of deleterious substances, and this could mean that occasional use of marijuana might not be as risky for enhancing the chance of future cardiac events—or at the least, might be less risky,” Dr. Wright explains.

People who use marijuana more frequently might also be using it to soothe co-occurring conditions, which could be responsible for increasing their risk for cardiovascular events, he adds.

“These confounders make it impossible to state with conviction that marijuana leads to higher likelihood of cardiac events, even if the drug indeed has such an effect,” Dr. Wright says.

 

Marijuana’s research roadblocks

 

Researchers’ “understanding of the safety and efficacy of cannabis has been limited by decades of worldwide illegality and continues to be limited in the United States by the ongoing classification of cannabis as a Schedule 1 controlled substance,” the AHA wrote in its 2020 statement.

 American Heart Association. Marijuana use linked with increased risk of heart attack, heart failure. November 6, 2023.

Page RL, Allen LA, Kloner RA, et al. Medical marijuana, recreational cannabis, and Cardiovascular Health: A Scientific Statement from the American Heart Association.Circulation. 2020;142(10).

 

 

This impact is profound, affecting how doctors can treat and advise patients.

“We are only now beginning to better understand the effect of cannabis use on heart health,” Dr. Chen says. “We have known that THC has effects on the cardiovascular system, such as increasing sympathetic tone, endothelial dysfunction, and oxidative stress, but it is only in the last few years that researchers have gathered data associating cannabis use [with] worsened clinical cardiovascular outcomes.”

At the end of the day, “any form of cannabis use does involve some risk to your health,” Dr. Chen adds. “Everyone has to decide for themselves how much risk they want to expose themselves to.”

Dr. Wright encourages doctors to take the research seriously but not to use marijuana or cannabis as a sole determinant of a person's heart health risks. 

Encourage at-risk patients to prioritize general health management and to “make sure that elevated cholesterol, diabetes, and high blood pressure are controlled; that exercise is regularly undertaken; that cigarettes are completely avoided; and that obesity and poor diet are avoided, ” he says.