• Posted January 11, 2024

Could Medical Marijuana Be Bad for Heart Patients?

Medical marijuana might help ease chronic pain, but it also slightly increases a patient's risk of a dangerous abnormal heart rhythm, a new study says.

Patients treated with medical cannabis had a nearly 1% increased risk of being diagnosed with a heart rhythm problem that required monitoring and possible treatment, results show.

The risk was more than double that of chronic pain patients not using cannabis, and occurred within six months of starting medical weed.

“I don't think this research should make patients with chronic pain refrain from trying medical cannabis if other treatment has been inadequate,” said researcher Dr. Anders Holt, a cardiologist at Copenhagen University Hospital in Denmark.

“However, these results do suggest some improved monitoring may be advisable initially, especially in patients who are already at increased risk of cardiovascular disease,” he added in a news release.

Medical weed is now allowed as a treatment for chronic pain in 38 U.S. states, as well as in several countries in Europe, Holt noted.

“This means more and more doctors will find themselves prescribing cannabis, despite a lack of evidence on its side effects,” he said.

To better inform these prescriptions, Holt and his colleagues conducted what they believe is the first nationwide study to investigate the heart effects of medical marijuana prescribed for chronic pain.

For the study, researchers tracked nearly 5,400 Danish patients who were prescribed cannabis for chronic pain. They were compared with nearly 27,000 chronic pain patients not using cannabis as a treatment.

Patients using medical weed had a 0.8% risk of being diagnosed with a heart rhythm problem, researchers found. That's more than twice the odds of someone who wasn't taking the drug.

The largest increases in risk occurred among people who were 60 or older, as well as those already diagnosed with a chronic condition like cancer, heart disease, stroke or diabetes, results showed.

However, the study didn't find any link between cannabis use and an increased risk of heart attack, stroke or heart failure, researchers added.

“We need much more research in this area. Before concluding anything, results from this study should be replicated in other countries and settings,” Holt said. “It would also be interesting to understand if there are any links between long-term cannabis use and heart failure, stroke, or acute coronary syndrome. This would be an important area to clarify since chronic pain can persist for many years.”

The results show that doctors need to keep a close eye on the potential side effects of medical marijuana, says an editorial accompanying the study written by Robert Page, a professor of clinical pharmacy and physical medicine at the University of Colorado Anschutz Medical Campus in Aurora.

“These findings suggest that medical cannabis may not be a 'one-size-fits-all' therapeutic option for certain medical conditions,” Page said, adding that doctors should consider a patient's other illnesses before prescribing weed.

The new study appears in the European Heart Journal.

More information

The U.S. Centers for Disease Control and Prevention has more about the health effects of marijuana.

SOURCE: European Heart Journal, news release, Jan. 11, 2024