Recreational Marijuana Use: Is it Safe for Your Patient?

M arijuana is a very old drug with documented use reaching back to Chinese emperors and Egyptian pharaohs. Ancient civilizations described the medicinal value of marijuana, promoting it for its healing powers, antiinflammatory properties, and as a treatment for many different disease states. In the several intervening millennia, the medicinal claims surrounding marijuana use have been validated in many cases, and therapeutic benefits have been described for a variety of medical conditions. Today medicinal marijuana plays an important role in the management of chronic neuropathic pain, glaucoma, multiple sclerosis, HIV, and other conditions associated with chronic pain. In light of clinical evidence in support of medical marijuana, a number of countries as well as 20 individual states and the District of Columbia in the United States have legalized marijuana for medicinal purposes. Interestingly, legalization was extended to include recreational use in the states of Colorado and Washington, with additional referendums pending in several other states including Alaska, Arizona, Maine, Missouri, Montana, Oregon, and Wyoming. While the role of medical marijuana is indisputable in patients suffering from chronic, debilitating pain, the potential for widespread legalization of marijuana for recreational purposes raises important questions regarding safety. For example, do we really know enough about the cardiovascular effects of marijuana to feel comfortable about its use in patients with known cardiovascular disease or patients with cardiovascular risk factors? As early as 1972, Beaconsfield et al showed that marijuana smoking resulted in tachycardia. A decade later, the surgeon general of the United States issued a warning on the use of marijuana, describing it as a major public health problem, based on findings that marijuana consumption leads to a variety of cognitive, behavioral, and other systemic problems including respiratory, reproductive, and immunological disturbances. Here, we will focus on the cardiovascular effects of marijuana and the implications for recreational use. We recently reviewed reports in the literature that described a temporal association between marijuana use and serious cardiovascular events (Table). Several instances of temporal association between marijuana use and myocardial infarction were reported in the literature. In cases where marijuana use was linked to myocardial infarction, patients tended to be younger and have no other risk factors for infarction. The 2006 CARDIA study showed that marijuana use is associated with hypertension, dyslipidemia, and higher caloric intake, all of which may increase the incidence of coronary artery disease. In light of the probable effects of marijuana on increasing platelet coagulability and its frequent combined use with smoking tobacco or other illicit drugs, it is not surprising to note these reports of myocardial infarctions. In a review of 3882 patient interviews, Mittleman et al found a significant 4.8-fold increase in the incidence of myocardial infarction over baseline in the first hour after marijuana use. Similarly, a 4.2-fold increase in mortality rate was observed in marijuana users compared with nonusers following myocardial infarction. There is some suggestion that heavy marijuana use may lead to no-reflow phenomenon in both the heart and brain, implying an effect on small vessels and arterioles. In addition to myocardial infarction, marijuana use has also been temporally related to cardiac arrhythmia, cardiomyopathy, and arteritis. Similarly, several reports of cerebrovascular events have been described in association with marijuana inhalation ranging from transient ischemic events to strokes. The most striking feature of these events is incidence in very young patients with no other risk factors. No-reflow or cerebral artery spasm has been implicated, but the exact mechanism is not well established. Regardless of the mechanism, the evidence in the literature suggested to us The opinions expressed in this article are not necessarily those of the editors or of the American Heart Association. From the Department of Cardiology, Marshfield Clinic, Marshfield, WI (S.R.); Division of Cardiovascular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA (R.A.K.). Correspondence to: Shereif Rezkalla, MD, FACP, FACC, Department of Cardiology, Marshfield Clinic – Marshfield Center, 1000 N. Oak Ave., 2D2, Marshfield, WI 54449. E-mail: [email protected] J Am Heart Assoc. 2014;3:e000904 doi: 10.1161/JAHA.114.000904. a 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.