Cannabis dependence and abuse nearly doubled risk of heart attack post-surgery

Patients with active cannabis dependence and abuse were nearly twice as likely to suffer a heart attack after surgery, according to a study led by researchers at St. Michael's Hospital of Unity Health Toronto.

The study, published in the Online First edition of Anesthesiology, the peer-reviewed medical journal of the American Society of Anesthesiologists (ASA), also found the prevalence of cannabis dependence or abuse recorded among surgical patients increased significantly over the last decade.

Researchers analyzed the records of over 4 million adults in the United States from 2006 to 2015 undergoing one of 11 common elective procedures including knee or hip replacement, gallbladder removal, caesarian section, hysterectomy, and hernia repair.

"While cannabis is often purported as being safe or benign, we don't fully understand the health implications of this drug, particularly in heavy users," said Dr. Karim Ladha, a clinician-scientist at the Li Ka Shing Knowledge Institute of St. Michael's Hospital and lead author of the study.

"The results of this study make it clear that we need to pay more attention to cannabis users undergoing surgery," said Dr. Ladha.

Dr. Ladha noted that this research was the first step in determining whether there is any association between cannabis use disorders and perioperative outcomes. Dr. Ladha's subsequent work will prospectively follow patients with self-reported cannabis use disorder undergoing surgery using a more detailed method of data collection to determine if the association persists.

The findings did not show a difference in overall outcomes between patients who had a cannabis use disorder and those who did not. However, in addition to increased cardiac risk, there was evidence that patients with cannabis use disorders were possibly at an increased risk for a stroke.