Question - The reference cited below notes “Long-term inhalation of cannabinoids can be associated with the appearance of symptomatic sinus bradycardia and sinus arrest that can lead to asystole with syncope.” What is the mechanism for this observed effect in some cannabinoid users?
Answer - The cited article reports “Prolonged THC ingestion in human volunteers and mongrel dogs has been associated with the following: parasympathetic dominance that features sinus bradycardia; accentuated reflex bradycardia to exogenous catecholamines; enhanced withdrawal of sympathetic tone; and attenuated circulatory responses to exercise in keeping with centrally mediated enhanced parasympathetic activity and reduced sympathetic activity.” (Heckle MR et al. Cannabinoids and symptomatic bradycardia. 2018 Am J Med Sci 355(1):3-5)