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  • A new study looks at how drugs including cannabis, opioids, cocaine and methamphetamine can increase your risk of atrial fibrillation (AFib.)
  • AFib risk was highest among people who took cocaine or opioids. But all four drugs increased the risk of AFib.
  • In the study, researchers identified nearly 1 million people who had no pre-existing AFib, but who were diagnosed with this condition during the study period.
  • Experts say particulate matter in cannabis smoke may be responsible for increase in AFib risk.

Several commonly used illicit drugs increase the risk of atrial fibrillation (AFib), a potentially deadly heart-rhythm disorder, a new study shows.

These include methamphetamine, cocaine and opiates. But another drug that researchers found increases the risk of AFib is cannabis, which is legal in many US states for medical and/or recreational use.

“To my knowledge, this is the first study to look at marijuana use as a predictor of future atrial fibrillation risk,” study author Dr. Gregory Marcus, a cardiologist and professor of medicine at the University of California, San Francisco, said in a news release.

In the study, published Oct. 18 in the European Heart Journal, researchers analyzed data for every hospital admission, emergency room visit, and medical procedure in California that occurred from 2005 through 2015.

Using this data, they identified nearly one million people who had no pre-existing AFib, but who were diagnosed with this condition during this period.

They also identified patients whose medical records indicated they had used methamphetamine, cocaine, opiates or cannabis.

Based on this information, researchers estimated that cannabis users had a 35% higher risk of developing AFib, compared to people with no record of using cannabis.

In contrast, methamphetamine increased AFib risk by 86%, cocaine by 61% and opiates by 74%.

In their analysis, the authors of the new study took into account other factors that might affect a person’s AFib risk, such as age, sex, high blood pressure, diabetes, and use of one of the other three types of drugs examined in the study.

Although cannabis use increased the risk of AFib less than the other drugs, “cannabis use still exhibited an association of similar or greater magnitude to risk factors like dyslipidemia, diabetes mellitus, and chronic kidney disease,” the researchers wrote.

In addition, cannabis use increased AFib risk a similar amount as traditional tobacco use, they said.

Atrial fibrillation is the most common type of treated heart-rhythm disorder, or arrhythmia. This condition causes the heart to beat too slowly, too quickly or in an irregular way.

As a result, blood doesn’t flow as well as it should from the upper chambers of the heart (atria) to the lower chambers of the heart (ventricles).

This can cause symptoms such as an irregular heartbeat, fluttering or pounding of the heart, lightheadeness, extreme fatigue, shortness of breath, or chest pain. Some people with AFib may have no symptoms.

An estimated 12.1 million Americans will have AFib in 2030, according to the Centers for Disease Control and Prevention.

In addition, AFib was the underlying cause for over 26,000 deaths in 2019, and was mentioned on over 180,000 death certificates that year.

Methamphetamine and cocaine use have previously been shown to increase the risk of cardiovascular disease, including heart arrhythmias.

Dr. Muhammad Afzal, a cardiac electrophysiologist at The Ohio State University Wexner Medical Center in Columbus, said the increased risk of AFib seen in the new study in people who used methamphetamine, cocaine or opiates is not surprising.

“It is very likely that these substances led to aberrations of the autonomic nervous system, which is a known trigger for the initiation of atrial fibrillation,” said Afzal, who was not involved in the new research.

“Similarly, cannabis is known to influence the part of the autonomic nervous system that controls the heart,” he added.

Some previous research has also suggested that cannabis may cause heart rhythm problems, including AFib, although this evidence is not as strong as that for methamphetamine and cocaine.

The new study provides a better understanding of the AFib risks associated with cannabis use.

Researchers did not look at specific compounds in cannabis that might increase the risk of AFib, but Marcus said in the news release that particulate matter in cannabis smoke may be responsible.

Exposure to particulate matter in air pollution has been linked to an increased risk of AFib.

Afzal said particulate matter in cannabis smoke is a “plausible” explanation for the increased risk of AFib.

He pointed out that about one-third of cannabis users in the study also used tobacco.

“Cannabis use alone, or the combination of cannabis with smoking and alcohol, will increase the risk of developing atrial fibrillation,” he said.

Moderate to heavy alcohol use is also a risk factor for AFib.

Afzal emphasized that additional research is needed in order to better understand the AFib risks of cannabis and other drugs.

In the meantime, “cannabis users should be aware of the risk of atrial fibrillation, and try to minimize any other concomitant risk factors [they might have] for atrial fibrillation,” he said.