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Medical cannabis increases risk of heart arrhythmia

A new study presented at the European Society of Cardiology (ESC) Congress 2022 has found that cannabis prescribed for chronic pain in Denmark between 2018 and 2021 was associated with a higher risk of heart rhythm disorders (arrhythmias).

 “Chronic pain is a rising problem. According to Danish health authorities, 29 precent of Danish adults over 16 years of age reported chronic pain in 2017, up from 19 percent in 2000,” said study lead author Nina Nouhravesh, a cardiologist at the Gentofte University Hospital

“Medical cannabis was approved in January 2018 on a trial basis in Denmark, meaning that physicians can prescribe it for chronic pain if all other measures, including opioids, have proven insufficient. Safety data are sparse, hence this study investigated the cardiovascular side effects of medical cannabis, and arrhythmias in particular, since heart rhythm disorders have previously been found in users of recreational cannabis.”

In Denmark, medical cannabis comes in various formulations depending on its tetrahydrocannabinol (THC) and cannabidiol (CBD) levels: dronabinol (high THC), cannabinoid (more THC than CBD), and cannabidiol (high CBD) can all be prescribed to treat various conditions, including chronic pain.

The scientists identified a total of 1.6 million patients diagnosed with chronic pain between 2018 and 2021, with 4,931 of them using medical cannabis to address these problems (dronabinol 29 percent, cannabinoids 46 percent, and cannabidiol 25 percent). By following the participants for 180 days and comparing their risk of new cardiovascular conditions with individuals from a control group, the researchers found that the absolute risk of new-onset arrhythmia was 0.86 percent in medical cannabis users compared with 0.49 percent in non-users, for a relative risk of 1.74.

 “Our study found that medical cannabis users had a 74 percent higher risk of heart rhythm disorders compared with non-users; however, the absolute risk difference was modest. It should be noted that a higher proportion of those in the cannabis group were taking other pain medications, namely non-steroidal anti-inflammatory drugs (NSAIDs), opioids and anti-epileptics, and we cannot rule out that this might explain the greater likelihood of arrhythmias,” Dr. Nouhravesh explained. 

“Since medical cannabis is a relatively new drug for a large market of patients with chronic pain, it is important to investigate and report serious side effects. This study indicates that there may be a previously unreported risk of arrhythmias following medical cannabis use. Even though the absolute risk difference is small, both patients and physicians should have as much information as possible when weighing up the pros and cons of any treatment,” she concluded. 

By Andrei Ionescu, Staff Writer  

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