Cannabis has been used by indigenous populations for thousands of years for recreational and medicinal uses and following its decriminalization and legalization the availability of cannabis, and its use is expected to increase dramatically worldwide in various modalities, including smoking, hookah, vaping and edibles.
Medical marijuana and synthetic cannabinoids have been associated with adverse cardiovascular effects, although the long-term cardiovascular effects of using cannabis have been uncertain.
A review article published in Nature Review has filled some gaps in knowledge.
The effects of cannabis are mediated by cannabinoid receptor 1 (CB1) and CB2, which belong to the G protein-coupled receptor(GPCR) superfamily with CB1 is the most abundant in the brain, but also expressed in peripheral tissues, including the heart and vasculature while CB2 is expressed largely in immune cells and the vasculature. Both CB1 and CB2 receptors are involved in the progression of atherosclerosis. CB1 stimulation has acute dose-dependent hemodynamic effects, including increasing heart rate and blood pressure, myocardial contractility and vascular tone. By contrast, CB2 stimulation does not produce substantial hemodynamic effects. However, under pathological conditions, CB2 can be upregulated in endothelial cells and can have attenuating vascular inflammation and pro-inflammatory response.
The effects of cannabinoids on various risk factors are emerging, and their mechanistic role in the pathogenesis of cardiovascular disease is distinct from that of traditional tobacco smoking. Robust evidence from basic science and clinical studies supports the association between cannabis use and cardiovascular diseases. Cannabis has now been shown to be associated with adverse cardiovascular events, and heavier use is associated with a greater risk. In the YOUNG-MI registry, a retrospective cohort study of young adults (aged ≤50 years) with myocardial infarction, cannabis users were more likely than non-users to have a premature myocardial infarction. The Determinants of MI Onset Study (MIOS) prospectively followed up 3,886 patients with MI and found that mortality was 29% higher in chronic users of cannabis than in non-users.
In a retrospective study from a Danish registry in 5,391 patients with chronic pain who used cannabis, a link was reported between cannabis use and new-onset arrhythmias (atrial fibrillation or flutter, conduction disorders, paroxysmal tachycardia and ventricular arrhythmias. After cannabis exposure, heart rate transiently increases due to increased sympathetic tone and decreased parasympathetic tone. The chronic use of cannabis results in bradycardia due to reversal of autonomic tone.
Moreover, the burden of cannabis-related arrhythmic events is exacerbated in individuals with ischemic heart disease compared with those without. Mounting data contradicts the common perception that cannabis is safe and have demonstrated that cannabis use can harm the cardiovascular system and like tobacco pose serious cardiovascular health problems.
Supporting Reference: The relationship between cannabis and cardiovascular disease: clearing the haze NATURE REVIEWS CARDIOLOGY.
By Dr. Nanna
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