Active users of marijuana may be doubling their risk of stress cardiomyopathy, a malfunction of the heart muscle malfunction that can mimic the symptoms of a heart attack, a new study has found.

According to a paper presented at the American Heart Association’s Scientific Sessions 2016 in Louisiana, researchers found that people who used marijuana  were twice as likely to develop a heart condition called transient ventricular regional ballooning (TVRB) – a form of  cardiomyopathy . The condition leads to a sudden weakening of the heart muscle with symptoms including chest pain, shortness of breath and dizziness, although often temporary.

“The effects of marijuana, especially on the cardiovascular system, are not well known yet. With its increasing availability and legalization in some states, people need to know that marijuana may be harmful to the heart and blood vessels in some people,” said study co-author Amitoj Singh, chief cardiology fellow at the Pennsylvania-based St. Luke's University Health Network, in a press release.

For the research, 33,343 people hospitalized with stress cardiomyopathy between 2003-2011 in the U.S. were identified from the Nationwide Inpatient Sample’s database. Less than one percent of this number – 210 people ­– was identified as marijuana users.

According to the study, the marijuana users were comparatively younger males with fewer cardiovascular risk factors, like less high blood pressure, diabetes and high cholesterol. Despite this, during stress cardiomyopathy, the marijuana users had a significantly higher likelihood of going into cardiac arrest.

“This development of stress cardiomyopathy in younger patients who used marijuana suggests a possible link that needs to be further investigated,” said co-author Sahil Agrawal, a chief cardiology fellow at St. Luke's, in the release.

The marijuana users were also more likely to be depressed, suffer from psychosis or anxiety disorders as well as have a history of alcoholism, tobacco and substance abuse, as compared to patients who did not use marijuana.

Despite putting forward observational conclusions, the study could not analyze the time frame for which the patients were using marijuana or the time after which the stress cardiomyopathy occurred. As an observational study, it could also not show a direct cause and effect and as the database was a regional one, there was no information on state-wise marijuana use.