In a new study, researchers used data from a database called the French Addictovigilance Network, gathered from 2006 to 2010. Of the nearly 2,000 reported complications related to marijuana, the researchers found that 2 percent, or 35 cases, involved heart problems. These cases included 20 people who suffered a heart attack, and nine who died.

Researchers found most patients were men, with an average age of about 34. Regular marijuana users with a family history of heart disease had an increased risk of heart disease, according to the study, published today (April 23) in the Journal of the American Heart Association.

Many of the patients also had other risk factors for heart disease, such as smoking tobacco and drinking alcohol, the researchers noted. Nevertheless, nearly half of the patients were regular users of only marijuana.