in separate studies.
Rhushik Bhuva, MD, presented the recurrent-MI results from a national U.S. study, and Sang Gune K. Yoo, MD, presented the PCI study, which used data from a Michigan cohort. The studies were presented at the American Heart Association scientific sessions.
Both studies “add to our accumulating knowledge of the cardiovascular risks of marijuana,” Ersilia M. DeFilippis, MD, a cardiology fellow at Columbia University Irvine Medical Center, New York, who was not involved with this research, said in an interview.
Dr. DeFilippis and the two study authors say clinicians and patients need to be more aware of cardiovascular risks from smoking marijuana, and they call for more patient screening, counseling, and research.
Need for screening and counseling
Marijuana is a Schedule 1 controlled substance in the United States, which makes it illegal to conduct rigorous controlled trials of marijuana products. Existing knowledge is therefore based on observational studies, Dr. DeFilippis noted.
She was lead author of a review of marijuana use by patients with cardiovascular disease. The review was published in the Journal of the American College of Cardiology. An AHA scientific statement about marijuana and cardiovascular health was published in Circulation.
Both documents drew attention to risks from marijuana use in patients with cardiovascular disease.
Until more data are available, “I think it is absolutely critical” that cardiologists and general providers screen patients for marijuana use, “either at the time of their MI or ideally prior to that, when they are making a cardiovascular risk assessment,” said Dr. DeFilippis.
That is also the time to “counsel patients, especially those who have had an MI, about risks associated with continuing to use marijuana.”
Importantly, providers and patients need to be aware that “cannabinoids, through the cytochrome P450 system, can interact with well-known cardiovascular medications, which we know provide benefit in the post-MI period,” she added. “For example, marijuana can interfere with beta-blockers, statins, antiarrhythmics, and certain anticoagulants.”
Dr. Bhuva, a cardiology fellow with the Wright Center for Community Health, Scranton, Pa., said that it is “concerning” that “recurrent heart attacks and cardiac interventions [were] higher among cannabis users, even though they were younger and had fewer risk factors for heart disease.
“Spreading awareness regarding the potential risk of recurrent heart attacks in middle-aged, African American, and male cannabis users and screening them at an earlier age for potential risk factors of future heart attacks should be encouraged among clinicians,” he urged in a statement from the AHA.
Dr. Yoo, an internal medicine resident at the University of Michigan, Ann Arbor, pointed out that, in their study of patients who underwent PCI after MI or because they had coronary artery disease, those who smoked or vaped marijuana were younger and were more likely to be male. They were less likely to have traditional cardiovascular risk factors except for smoking tobacco, which was highly prevalent.
After propensity matching, patients who used marijuana had a 1.5-fold increased risk of in-hospital bleeding and an 11-fold higher risk for in-hospital stroke following PCI.
However, the absolute number of strokes in PCI was small, and the confidence interval was wide (indicating a large uncertainty), Dr. Yoo said in an interview.
These risks “should not deter patients from undergoing these [lifesaving] procedures,” he said; however, clinicians should be aware of these risks with marijuana use and should screen and counsel patients about this.