Though marijuana is now prescribed by medical professionals to help some patients cope with their health conditions, a new study shows that the drug could still do harm if used too frequently.

A new study presented at this year’s American Heart Association’s (AHA) Scientific Sessions in New Orleans, shows that frequent marijuana use could put people at risk for developing stress cardiomyopathy. In a study conducted at St. Luke’s University Health Network in Bethlehem, Pennsylvania, researchers found that marijuana users were twice as likely to develop stress cardiomyopathy than those who didn’t use it.

“The effects of marijuana, especially on the cardiovascular system, are not well known yet,” said Amitoj Singh, MD, study co-author and chief cardiology fellow at St. Luke’s, in a statement from AHA. “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.”

Nationwide Inpatient Sample data showed that of the more than 33,000 people who were hospitalized with stress cardiomyopathy between 2003 and 2011 in the U.S., 210 also were marijuana users.  Those users were also predominantly younger and male. Active marijuana use was determined based on information provided by the patient and urine tests.

Additionally, the data showed that while experiencing stress cardiomyopathy, marijuana users were more likely to go into cardiac arrest and require a defibrillator.

“If you are using marijuana and develop symptoms such as chest pain and shortness of breath, you should be evaluated by a healthcare provider to make sure you aren’t having stress cardiomyopathy or another heart problem,” Singh said.