Use of Medical Cannabis Linked to Increased Risk of Arrhythmia

Marijuana gummies are pictured in a file photo. Victor Moussa/Shutterstock

Using medical cannabis for chronic pain management could put patients at risk for developing arrhythmia, a new study reports.

The study comes out of Denmark, which is one of more than 40 countries worldwide that has legalized the use of medical cannabis for adult use.

Researchers recruited 5,391 individuals experiencing chronic pain who had never before used cannabis. Their pain symptoms stemmed from arthritis, back issues, slipped discs, complicated fractures, cancer, neurological diseases, headaches, and other unspecified pain diagnoses. Just under two-thirds of the patients were women (63.2 percent), and the average age of the participants was 59 years old. Many had experience taking NSAIDs, opioids, anti-epileptics and antidepressants to deal with their pain. Some also took beta-blockers and antihypertensive drugs.

During the study, just under half of the patients (47 percent) received medical cannabis with just THC, 24 percent of the patients received medical cannabis with just CBD, and 29 percent received medical cannabis with a combination of the two properties.

An additional 26,941 patients were recruited to serve as a control group. The control group did not receive cannabis as a treatment.

The research team found that within 180 days of follow-up, 42 patients developed new onset arrhythmia. New arrhythmias were most common in patients with cancer or cardiometabolic diseases.

Arrhythmia occurs when the heart begins to beat irregularly. It may beat too quickly, too slowly or with an irregular rhythm. When left untreated, arrhythmia can damage the heart, brain and other vital organs. Arrhythmias can also lead to life-threatening strokes, heart failure or cardiac arrest.

Additionally, the research team found that among the patients exposed to cannabis for the first time, 22 experienced stroke and 13 experienced heart failure for the first time. However, patients in the control group also experienced heart failure and stroke, leading the researchers to find “no significant associations” between first-time stroke or heart failure and medical cannabis use.

“Despite a low absolute risk difference, this is vital knowledge for any prescribing physician due to the rising demand for medical cannabis as pain treatment,” the research team wrote.

It is noted in the study that the rate of onset of new arrhythmias caused by medical cannabis is similar to the rates found in patients treated with opioids, anti-epileptics and NSAIDs.

Is THC or CBD Worse?

THC, or delta-9-tetrahydrocannabinol, is the psychoactive component of cannabis. This is the compound responsible for making a person “feel high” when consuming cannabis. CBD, which is short for cannabidiol, is also made from cannabis. While it is related to THC, it doesn’t contain psychoactive components and doesn’t give a person a euphoric “high.” CBD is often prescribed as a pain reliever.

While the research team didn’t identify whether patients on THC, CBD or a combination of the two had higher rates of arrhythmia, they noted that THC triggers the body’s parasympathetic nervous system, which is responsible for maintaining the body’s resting heart rate. Also responsible for keeping the body in ‘fight or flight’ mode, constant flickers or triggers of the system could cause the heart to develop arrhythmic states.

The study added that previous research also points to a strong association between THC and cardiovascular events. The U.S. Centers for Disease Control and Prevention (CDC) notes that marijuana can increase the heart rate and blood pressure immediately after use while also increasing the risk of stroke, heart disease, and other vascular diseases.

The CDC notes, however, that “It is hard to separate the effects of marijuana chemicals on the cardiovascular system from those caused by the irritants and other chemicals that are present in the smoke” and that more research is needed to fully understand the impact of cannabis use on the cardiovascular system.