AHA on Cannabis: No Evidence of Heart Benefits, but Potential Harms

Heidi Splete

August 07, 2020

Evidence for a link between cannabis use and cardiovascular health remains unsupported, and the potential risks outweigh any potential benefits, according to a scientific statement from the American Heart Association.

The increased legalization of cannabis and cannabis products in the United States has driven medical professionals to evaluate the safety and efficacy of cannabis in relation to health conditions, wrote Robert L. Page II, PharmD, of the University of Colorado, Aurora, and colleagues.

In a statement published in Circulation, the researchers noted that although cannabis has been shown to relieve pain and other symptoms in certain conditions, clinicians in the United States have been limited from studying its health effects because of federal law restrictions. "Cannabis remains a schedule I controlled substance, deeming no accepted medical use, a high potential for abuse, and an unacceptable safety profile," the researchers wrote.

The statement addresses issues with the use of cannabis by individuals with cardiovascular disease or those at increased risk. Observational studies have shown no cardiovascular benefits associated with cannabis, the writers noted. The most common chemicals in cannabis include THC (tetrahydrocannabinolic acid) and CBD (cannabidiol).

Some research has shown associations between CBD cardiovascular features including lower blood pressure and reduced inflammation, the writers noted. However, THC, the component of cannabis associated with a "high" or intoxication, has been associated with heart rhythm abnormalities. The writers cited data suggesting an increased risk of heart attacks, atrial fibrillation and heart failure, although more research is needed.

The statement outlines common cannabis formulations including plant-based, extracts, crystalline forms, edible products, and tinctures. In addition, the statement notes that synthetic cannabis products are marketed and used in the United States without subject to regulation.

"Over the past 5 years, we have seen a surge in cannabis use, particularly during the COVID-19 pandemic here in Colorado, especially among adolescents and young adults," Dr. Page said in an interview. "Because of the surge, health care practitioners need to familiarize themselves with not only the benefits, but risks associated with cannabis use regardless of the formulation," he said.

As heart disease remains a leading cause of death in the United States, understanding the cardiovascular risks associated with cannabis is crucial at this time, Dr. Page said.

Dr. Page noted that popular attitudes about cannabis could pose risks to users' cardiovascular health. "One leading misconception about cannabis is because it is ‘natural' it must be safe," Dr. Page said. "As with all medications, cannabis has side effects, some of which can be cardiovascular in nature," he said. "Significant drug-drug interactions can occur as CBD and THC, both found in cannabis, inhibit CYP3A4, which metabolizes a large number of medications used to treat many cardiovascular conditions," he noted.

"Unfortunately, much of the published data is observational in nature due to the federal restrictions on cannabis as a schedule I drug," said Dr. Page. "Nonetheless, safety signals have emerged regarding cannabis use and adverse cardiovascular outcomes, including myocardial infarction, heart failure, and atrial fibrillation. Carefully designed prospective short- and long-term studies regarding cannabis use and cardiovascular safety are needed," he emphasized.

Areas in particular need of additional research include the cardiovascular effects of cannabis in several vulnerable populations such as adolescents, older adults, pregnant women, transplant recipients, and those with underlying cardiovascular disease, said Dr. Page.

"Nonetheless, based on the safety signals described within this Clinical Science Statement, an open discussion regarding the risks of using cannabis needs to occur between patient and health care providers," he said. "Furthermore, patients must be transparent regarding their cannabis use with their cardiologist and primary care provider. The cannabis story will continue to evolve and is a rapidly moving/changing target," he said.

"Whether cannabis use is a definitive risk factor for cardiovascular disease as with tobacco use is still unknown, and both acute and long-term studies are desperately needed to address this issue," he said.

Dr. Page had no relevant financial conflicts to disclose.

SOURCE: Page et al. Circulation. 2020 Aug 5. doi: 10.1161/CIR.0000000000000883.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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