Robert Harrington, M.D., FAHA, American Heart Association President and the Arthur L. Bloomfield professor of medicine and chair of the Department of Medicine at Stanford University, Stanford, California
copyright American Heart Association

"Symptomatic arrhythmias, rapid heart rates, irregular heart beats, rapid heart rates that make people feel dizzy or lightheaded, all of these are really common cardiovascular conditions, and clinicians are trained to ask a series of questions about associated use of drugs, of other products that may be associated with arrhythmias. This particular study is of interest because it raises the suggestion that perhaps use of cannabis-containing materials may, in fact, be associated with an increased risk of arrhythmia. 

It's not proving that there's a direct link, but it's raising a suggestion in an observational analysis that that indeed might be the case. What that means for clinicians is that if you're seeing a patient who is presenting with a symptomatic arrhythmia, adding cannabis usage to your list of questioning as you begin to try to understand possible precipitating factors for this arrhythmia seems to be a reasonable thing to do."