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It's turning out that cannabis may not be the panacea many once had professed it to be. While recreational consumption still appears to have a fairly low level of health risk for the average person, a new study suggests that there's a potential cardiovascular impact for those managing heart disease. We know that tobacco smoking leads to almost one in every four cardiovascular disease-related deaths. Studies on cannabis-related cardiovascular events have been primarily observational and self-reported, often pulling from small population samples without differentiation of consumption method. Some of those "studies" have suggested that marijuana can be the inducer for triggering heart attacks and strokes. Now there's something more concrete after a new report was published in the Journal of the American College of Cardiology, “Marijuana Use in Patients With Cardiovascular Disease.”
One of the authors of that report, Ersilia DeFilippis, MD, a cardiology fellow at Columbia University Irving Medical Center and New York-Presbyterian, said the study started looking into marijuana's effect on the heart a few years ago while studying heart attacks in people under 50.
“Some observational studies have suggested an association between marijuana and a range of cardiovascular risks,” said another author, Muthiah Vaduganathan, MD, MPH, of Brigham and Women’s Hospital’s Heart and Vascular Center in Boston. “We also know that marijuana is becoming increasingly potent. Our review suggests that smoking marijuana carries many of the same cardiovascular health hazards as smoking tobacco. While the level of evidence is modest, there’s enough data for us to advise caution in using marijuana for our highest-risk patients, including those who present with a heart attack or new arrhythmia, or who have been hospitalized with heart failure.”
Dr. DeFilippis stated, "We noted that 10% of patients in a registry of young heart attack patients had used marijuana and/or cocaine." She and her colleagues recently went through the medical literature to find out about the substance and limitations to previous studies. What they found, based on the responses to a National Health and Nutrition Examination Survey from 2016, was that over 2 million people with heart disease have used or continue to use marijuana.
Marijuana is an incredibly highly abused drug in the US. Approximately 90 million American adults have admitted to using it at least once in their lives, and over 39 million admit to having used marijuana in the past year.
"In addition to the 2 million marijuana users with diagnosed cardiovascular disease, many more may be at risk," Dr. DeFilippis says, "With many adolescents and young adults turning to marijuana, it is important to understand the cardiovascular implications they may face years down the line."
There is a common belief among researchers that cannabinoids may have the ability to increase the activity of some prescription drugs that are already in one's body. The review found that certain cardiovascular medications, including statins and blood thinners, could possibly be affected by marijuana use. However, there is limited data available to help direct physicians when adjusting dosages to compensate for marijuana use.
THC is the psychoactive chemical that one can ingest from smoking marijuana, but marijuana contains more than 100 other compounds, called cannabinoids, that are chemically related to THC and THCA. The percentage of THC that one can get from marijuana plants has steadily increased over the past 30 years mostly due to the evolution of the marijuana growing business and the technology around creating more potent marijuana.
"Higher potency may translate into greater effects on the conduction system, the vasculature, and the muscle of the heart," Dr. DeFilippis mentions. "It also highlights the need for real-world data given the variety of marijuana products and formulations available for purchase."
“Vaping marijuana is becoming more and more common, and we know vaping marijuana increases the pharmacological effects of the drug,” Dr. Vaduganathan said.
There are now many new ways now to ingest THC as well, which have also evolved with the advent of the legal marijuana business. Marijuana is now legal in 11 US states. Aside from smoking marijuana, users can now consume edible THC in candy and cookies. There is also more concentrated form of THC called "wax," which is a wax-like substance that is distilled from the marijuana plant and can be smoked but is most often vaped. The myriad of delivery methods have also evolved in their ability to elevate cannabinoid potency to even higher levels than simply smoking the plant.
Receptors for cannabinoids are highly concentrated in the nervous system but research shows that they also can be found in blood cells, muscle cells, and other tissues and organs. There has been a small experimental study that had found that THC ingestion could bring on angina, or chest pain, more quickly in people with coronary heart disease compared with smoking a placebo.
And while the current evidence for a link between marijuana and heart attacks is still emerging, many in the medical community feel that smoking marijuana may increase cellular stress and inflammation. All of which are known to be precipitating factors for coronary artery disease and heart attacks. There is also a belief that there is an association between marijuana use and cerebrovascular events, including strokes. The theory is that marijuana may induce changes in the inner lining of blood vessels or alter blood flow.
For patients who wish to continue to use marijuana, or who have other medically indicated reasons for use, the reviewers recommend limiting use as much as possible and for clinicians to inform patients that vaping or ingesting certain synthetic forms of cannabinoids, which are particularly potent, may have increased adverse effects.
The reviewers recommend that for some patients, cardiologists should test for marijuana use by urine toxicology screening. These include patients being considered for heart transplantation or those who present with early-onset heart attacks or heart failure at a young age.
"Although we need more data, the evidence we do have indicates that marijuana use has been associated with coronary artery disease, arrhythmia, cardiomyopathy, and more," Dr. DeFilippis says. "Therefore, asking patients about marijuana use may help in risk assessment. In addition, we know that marijuana use affects the metabolism of many common cardiac drugs. In order to make sure patients are getting therapeutic doses without untoward side effects, it is important for cardiologists to talk to their patients about marijuana use," she concludes.
Dr. Vaduganathan added, “Now that we have seen marijuana use become more popular than tobacco smoking, we need more rigorous research, including randomized clinical trials, to explore the effects of marijuana on cardiovascular health."
Reference: “Marijuana Use in Patients With Cardiovascular Disease” by Ersilia M. DeFilippis, Navkaranbir S. Bajaj, Amitoj Singh, Rhynn Malloy, Michael M. Givertz, Ron Blankstein, Deepak L. Bhatt and Muthiah Vaduganathan, 20 January 2020, Journal of the American College of Cardiology.