A review published in the Journal of the American College of Cardiology this month suggests that an excess of 2 million patients with cardiovascular disease also use marijuana.
The research, penned by Brigham and Women's Hospital cardiologist Muthiah Vanduganathan, MD, MPH, and colleagues, comes on the heels of cannabis legalization in Illinois and at a time when recreational marijuana use is climbing fast across the U.S. Despite that, the authors said, there’s still a lot we don’t know about how the drug affects human health.
What we do know about marijuana’s effect on CV wellness—like the fact that inhaling cannabis can raise a person’s heart rate and lower their blood pressure—is largely limited to observation. Marijuana is classified as a schedule I drug by the U.S. Drug Enforcement Agency, so its use in research settings is highly restricted and subject to approval from local, state and federal agencies. Right now, randomized clinical trials dealing with cannabis just aren’t feasible.
Instead, researchers, including Vanduganathan and his team, turn to real-world data to study the effects of cannabis on the American population, comparing before-and-after statistics on health in states that have legalized the drug. The authors’ analysis dealt with data from the 2015-2016 National Health and Nutrition Examination Survey (NHANES), which revealed 89.6 million people that year reported using marijuana.
Of that subset, 2.3%—2 million adults—had concurrent cardiovascular disease.
“This was eye-opening for us,” Vanduganathan said in a release. “We’re experiencing an epidemiological shift. More patients are curbing their cigarette smoking, and we’re seeing big improvements in cardiovascular health for those who quit. In contrast, we’re seeing an accelerating use of marijuana and now, for the first time, marijuana users are exceeding cigarette smokers in the U.S. We now need to turn our attention and public health resources toward understanding the safety profile of its use.”
The team included in their review an outline of the ways the components of and compounds in marijuana might affect the heart at a molecular level, as well as a number of known drug interactions between cannabis and common CV medications. They also note that observational studies have suggested tenuous links between marijuana and smoking-related cardiotoxicity, coronary artery disease, arrhythmias and cerebrovascular disease.
In October of 2018, shortly after Canada legalized recreational cannabis countrywide, Taylor Lougheed, MD, MSc, lead physician at Cannabinoid Medical Clinic in Ottawa, told Cardiovascular Business that cannabis and heart disease is indeed a balancing act. He said patients with CVD might be at an increased risk of several conditions while using marijuana, so he suggests those patients avoid inhaling the drug orally to better protect themselves.
“In the clinic, patients often ask us about the safety of marijuana use and we’re pressed to offer the best scientific evidence,” Vanduganathan said. “Our current approach is that patients who are at high risk of cardiovascular events should be counseled to avoid or at least minimize marijuana use, and that rigorous scientific research should be conducted to further inform recommendations for patient care.”