Patients prescribed cannabis for chronic pain may face a heightened risk of experiencing heart rhythm issues, according to new research to be presented at ESC Congress 2022, the annual meeting of the European Society of Cardiology.
The study’s authors focused on data from 1.6 million patients who were diagnosed with chronic pain in Denmark from 2018 to 2021. The group’s median age was 60 years old, and 63% were women.
“Chronic pain is a rising problem,” lead author Nina Nouhravesh, MD, a cardiologist with Gentofte University Hospital in Denmark, said in a statement. “According to Danish health authorities, 29% of Danish adults over 16 years of age reported chronic pain in 2017, up from 19% in 2000. 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.”
Nouhravesh et al. found that nearly 5,000 patients from the cohort had at least one prescription for cannabis. The prescriptions were for a wide range of chronic pain conditions; the most common were cancer (17.8%), arthritis (17.1%) and back pain (14.9%). Each patient with a cannabis prescription was matched—by age, sex and pain diagnosis—to five control patients, and all participants were followed for 180 days.
Overall, the absolute risk of new-onset arrhythmia was 0.86% for patients with a cannabis prescription and 0.49% for patients without a cannabis prescription. The researchers described this as a “modest” difference, adding that there were other factors that could have been affecting the data.
“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, opioids and anti-epileptics, and we cannot rule out that this might explain the greater likelihood of arrhythmias,” Nouhravesh said in the same statement.
Even with these questions to consider, however, Nouhravesh emphasized why her team’s findings are still significant.
“This study indicates that there may be a previously unreported risk of arrhythmias following medical cannabis use,” she said. “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.”
ESC Congress 2022 is scheduled for August 26-29 in Barcelona. More information is available here.