The public needs high-quality information about cannabis, which can help counterbalance the proliferation of rumor and false claims about the health effects of cannabis products.

While some studies have linked the chemicals of cannabis to a risk for heart attack, much remains unknown about THC’s effects on the cardiovascular system. Here are the truths of what is known and what research has provided in an updated analysis of cannabis and the risk for cardiovascular effects.

Truth: We still need more research, but hands are tied

A 2017 study published in the Journal of Thoracic Disease stated that due to the rise of the recreational use of THC, researchers might be underestimating cannabis’ risk factors on the human body as well as the benefits.

Since cannabis continues to be listed as a Schedule 1 controlled substance, many organizations like the American Heart Association (AHA) have encouraged the Drug Enforcement Administration to review its designation and how it might hinder research. In August 2020, they explained in the journal Circulation:

“Because of the rapidly changing landscape of cannabis laws and marijuana use, there is a pressing need for refined policy, education of clinicians and the public, and new research. Laws should be harmonized in ways that limit confusion and better reflect the existing science behind cannabis, starting in the United States at the federal level with removal of cannabis from Schedule 1 of the US Controlled Substances Act, followed by a proactive approach to labeling that standardizes concentrations of THC and CBD content.”

The AHA also noted that multiple studies showcased different risk factors for heart complications, depending on the cannabis delivery device. They stressed the importance that individuals and care teams needed high-quality advice and studies about cannabis to understand its effects on the cardiovascular system better, saying, “The public needs high-quality information about cannabis, which can help counterbalance the proliferation of rumor and false claims about the health effects of cannabis products.”

Photo by onsuda/Getty Images

Truth: We are closer to answers on heart health and THC than ever before

In the first vote in over 50 years, the U.S. House of Representatives voted on the MORE Actto remove cannabis from the Controlled Substances Act in December 2020. Approved by a vote of 228 to 164, Arnold & Porter Kaye Scholer LLP advised:

“The MORE Act provides a key starting point for companies participating in or watching the growing cannabis market and context for understanding the dynamics and nature of the future federal legal framework. We will continue to monitor legislative developments in this area and encourage readers to contact the authors of this Advisory or their usual Arnold & Porter contact for more information.”

As the United States continues to discuss cannabis research and declassifying THC as a Title 1 drug, studies are bound to show conflicting analyses. A 2017 study showed that “among patients with heart failure, those who used marijuana were less likely to experience a complication called atrial fibrillation, or “A-fib,” a type of irregular heartbeat that can worsen heart failure symptoms.”Talk about confusing!

Truth: The risk appears to depend on the delivery of cannabis

Cannabis is known to raise the heart rate and create a temporary rise in how fast the heart pumps. For individuals with cardiovascular diseases (CVDs,) some studies have found a risk of stroke, while others showcased that CBD actually reduces blood pressure. In a piece for Healthline, Brigham and Women’s Hospital cardiologist Dr. Muthiah Vaduganathan shared that the delivery of cannabis depends on its impact on the heart. An April 2019 study published in the Annals of Internal Medicine (AIM) cited that edibles appeared to have a higher risk than vaping, though more research was needed.

Truth: The studies aren’t all created equal

In 2018, a systematic review of over two dozen studies featured in AIM found the following:

• 13 and 11 studies looked at marijuana use and cardiovascular risk factors
• Six studies suggested a “metabolic benefit from marijuana use.”
• Some studies’ evidence was insufficient and limited by recall bias, inadequate exposure assessment, minimal exposure, and more.

With new studies being added, scientists and associations alike are feeling hindered by the drug’s Schedule 1 status. With removal in the works, individuals and care teams can become better informed about the role cannabis plays in the human body and the heart.