Medical cannabis for pain 'increases heart problems'

Tuesday August 23rd 2022

Taking medical cannabis for chronic pain is associated with an increased risk of heart rhythm disorders, cardiologists will hear.

Danish research presented to the ESC Congress 2022 shows that although medical cannabis users had a 74% higher risk of heart rhythm disorders than non-users, the absolute risk difference was modest.

Study author Dr Nina Nouhravesh, of Gentofte University Hospital, said medical cannabis was approved in Denmark in January 2018 on a trial basis. Because there is little safety data this study investigated the cardiovascular side effects of medical cannabis.

Medical cannabis comes in various formulations depending on tetrahydrocannabinol (THC) and cannabidiol (CBD) levels. Dronabinol, which has high THC, cannabinoid, which has more THC than CBD, and cannabidiol, which has high CBD, can all be prescribed in Denmark.

The researchers identified 1.6 million patients diagnosed with chronic pain in Denmark between 2018 and 2021. The median age of participants was 60 years and 63% were women.

Of those, 4,931 patients (0.31%) claimed at least one prescription of cannabis, with 29% prescribed dronabinol, 46% cannabinoids, and 25% cannabidiol.

Each user was matched by age, sex and pain diagnosis to five non-users with chronic pain who acted as controls. Users and controls were followed for 180 days and were then compared for risks of new cardiovascular conditions.

The absolute risk of new-onset arrhythmia was 0.86% in medical cannabis users compared with 0.49% in non-users, for a relative risk of 1.74. The risks of new-onset acute coronary syndrome and heart failure did not differ between the two groups. The results were similar for each chronic pain condition and each type of medical cannabis.

Dr Nouhravesh said: “Our study found that medical cannabis users had a 74% 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.

“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.”

The abstract *Cardiovascular risk following cannabinoid treatment for patients with chronic pain* will be presented during the session *Drug cardiotoxicity: what do we need to know?* on Saturday 27 August.

Tags: Alternative Therapy | Europe | Heart Health | Pain Relief

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