Are electronic cigarettes associated with the risk of myocardial infarction and stroke? A systematic review and meta-analysis.

BACKGROUND: The existing studies in the literature have provided conflicting results on the association of e-cigarettes with myocardial infarction (MI) and stroke. Hence, the present systematic review and meta-analysis (SRMA) aimed at critically reviewing and summarizing the currently available evidence of the association of e-cigarettes with MI and stroke. METHODS: The protocol was registered with PROSPERO (CRD42023467397). A systematic search of databases including PubMed, Cochrane database, and Web of Science was conducted between January 2005 through June 2025 for observational studies and randomized trials evaluating the association of e-cigarettes with MI and stroke. The included studies were reviewed critically for appropriateness and absence of conflict of interest of the authors with regard to the topic of analysis. Quantitative synthesis was performed using a random effect model for summary estimate (meta-odds ratio, meta-OR) of MI and stroke in e-cigarette users. RESULTS: We included 12 studies providing a total of 26 estimates - 11 for MI (67,253 e-cigarette users and 363,622 non-users) and 15 for stroke (121,113 e-cigarette users and 1,064,228 non-users). Quantitative synthesis showed that e-cigarette users had a 1.53-times higher risk of MI than the non-e-cigarette users (95% CI 1.17-1.89). Adjusting for cigarette smoking as a confounder yielded similar results (meta-OR 1.24, 95% CI 1.11-1.37). The risk of MI was higher among current e-cigarette users who were former cigarette smokers than never-e-cigarette users (meta-OR 2.52, 95% CI 1.88-3.16). Similarly, stroke was found to be 1.05 times more frequent among e-cigarette users than non-users (95% CI 0.91-1.19). Restriction to studies adjusting for cigarette smoking as a confounder did not affect the results. The risk of stroke was 1.73 times higher among e-cigarette users who were former conventional cigarette smokers (95% CI 1.30-2.15) compared to non-e-cigarette users. CONCLUSIONS: The use of e-cigarettes may be linked with a higher risk of myocardial infarction as well as stroke, even after adjusting for cigarette smoking as a confounder or in those who were former conventional cigarette smokers. Further well-designed longitudinal studies are needed to confirm these findings and inform policymakers on the health effects of e-cigarette use.