Partner Series
Stroke, Heart Failure Linked to Marijuana
Credit: Brian Goodman/Shutterstock

Adults who use marijuana may have an increased risk of stroke and heart failure, according to a new study.

The people in the study who used marijuana were 26 percent more likely to have had a stroke at some point in their lives than those who did not use marijuana, the researchers found. The people who used marijuana were also 10 percent more likely to have developed heart failure at some point in their lives, compared with people who did not use marijuana, the researchers found.

The new findings suggest that, like many other medications, cannabis may have side effects, and that patients who use marijuana for medical reasons might need to be monitored for heart-related side effects of the drug, said lead study author Dr. Aditi Kalla, cardiology fellow at the Einstein Medical Center in Philadelphia. [25 Odd Facts About Marijuana]

However, the study had certain limitations, and more research is needed to examine the link between marijuana use and potential heart complications, she noted.

In the study, the researchers looked at the health records of more than 20 million patients ages 18 to 55 who had been admitted at more than 1,000 hospitals in the United States. The people in the study were discharged from the hospitals in 2009 and 2010, before marijuana use was legalized in many states.

The researchers looked at which patients had reported using marijuana, and then compared the rates of several types of cardiovascular disease between patients who reported using marijuana and those who reported not using the drug. The study will be presented on March 18 at the American College of Cardiology's 66th Annual Scientific Session in Washington.

One limitation of the study was that the researchers did not know if marijuana users in the study smoked or ingested the drug, the researchers said. The researchers were also unable to determine how much marijuana people used, or how often they used it, the scientists said. More research is needed to determine whether there is a certain dosage of cannabis beyond which a user may experience cardiovascular complications, Kalla told Live Science. [7 Ways Marijuana May Affect the Brain]

It is not clear why exactly cannabis use would be linked to a higher risk of heart failure, Kalla said. However, previous research has suggested that heart muscle cells have certain receptors that may be affected by use of the drug, and these receptors play a role in the heart's ability to contract, she said. When a person smokes marijuana, the heart's overall ability to contract may decrease, leading to heart failure, Kalla said.

It is also not clear why marijuana use would be linked to a higher risk of stroke, but previous research has suggested that using the drug may increase the chance of blood clots, which can then lead to stroke, Kalla said.

Future research should take a closer look at the relationship between marijuana use and heart disease, Kalla said. For example, researchers still need to figure out what amounts of marijuana and what forms of marijuana use (for example smoking or ingesting) may lead to cardiovascular complications, she said.

Originally published on Live Science.