Cannabis Use Variations and Myocardial Infarction: A Systematic Review

Background: Cannabis use is associated with an increased risk of coronary heart disease (CHD), including angina pectoris (AP), and myocardial infarction (MI). However, it is not clear whether cannabis use is an independent risk factor of AP and/or MI, because cannabis is often smoked together with tobacco. We investigated whether cannabis is an independent risk factor of MI and whether this risk is similar in cannabis smokers, cannabis vapers, and those who use cannabis edibles. Methods: A systematic review was performed, according to the PRISMA guidelines and using Medline (PubMed), Embase, and Google Scholar as databases. Results: Twenty-two eligible papers were identified. After adjustment for concurrent tobacco use, cannabis smoking remained significantly associated with incidents of MI, with aORs ranging between 1.03 and 5.24, and particularly high aORs in the younger age group. In never-tobacco smokers, frequent cannabis smoking was also associated with a significant MI risk (aOR = 1.88). Frequent and current cannabis use in any form other than smoking (e.g., vaping, but mostly ingestion) was not associated with a significantly increased cardiovascular risk (frequent use: aOR = 1.00 ns; current use: aOR = 1.31 ns). Conclusions: Like tobacco smoking, cannabis smoking may independently provoke MI. Vaping and ingestion of cannabis might be less harmful, probably because absence of combustion prevents exposure to certain toxins in cannabis smoke, including carbon monoxide.