E-cigarettes are particularly dangerous for former smokers, posing an elevated heart risk, according to a large meta-analysis suggesting that vaping is not cardiovascularly neutral – and raising questions about the devices as harm-reduction tools.
In a recent systematic review and meta-analysis published in BMC Public Health, researchers from the CMR-National Institute of Cancer Prevention and Research, Noida, India, and the Faculty of Medical Research, Academy of Scientific and Innovative Research (AcSIR), with others, investigated the association between electronic cigarettes and the risk of myocardial infarction (MI) and stroke.
The study pooled data from 12 observational studies involving large population samples to examine whether vaping is linked to cardiovascular outcomes while accounting for conventional cigarette smoking.
Analyses showed that e-cigarette users had 53% higher odds of MI compared with non-users. Notably, among former cigarette smokers who currently use vapes, the odds of a heart attack were more than doubled.
These findings raise concerns about the cardiovascular safety of e-cigarettes and indicate that they should not be assumed to be risk-free alternatives, said the scientists.
Smoking, vaping and CVD
Despite rapid global uptake, the cardiovascular safety of vapes remains controversial.
Studies have produced conflicting results, with some suggesting lower risk for exclusive vapers, while others were limited by cross-sectional designs, residual confounding by smoking history, or potential industry-related conflicts of interest.
As a result, a comprehensive analysis that carefully accounts for conventional cigarette smoking is needed to clarify the independent cardiovascular risks associated with vaping.
The present study addressed this gap using a systematic review and meta-analysis (SRMA) conducted in accordance with the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
Conventional cigarette smoking was treated as a key confounder and subgroup variable. Researchers searched PubMed, Cochrane Library, and Web of Science for studies published between January 2005 and June 2025. Eligible studies included observational designs and randomised trials involving human participants that reported the prevalence or incidence of MI or stroke.
Study selection, statistical methods
Studies with reported financial ties to the tobacco industry were excluded to minimise bias, and 12 studies met the inclusion criteria, comprising 430 875 participants for MI analyses and more than 1.1m participants for stroke analyses.
Random-effects models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) to quantify associations between e-cigarette use and cardiovascular outcomes.
Myocardial infarction and stroke findings
Overall, e-cigarette use was associated with a 53% higher odds of MI compared with non-use (OR 1.53, 95% CI 1.17–1.89). After adjustment for cigarette smoking, the association remained statistically significant but attenuated (OR 1.24, 95% CI 1.11–1.37).
Former cigarette smokers who currently use e-cigarettes had a 2.52-fold higher odds of MI compared with non-users (OR 2.52, 95% CI 1.88–3.16). The authors note that this may reflect residual confounding or cumulative effects of prior smoking rather than a direct causal effect of vaping alone.
Stroke outcomes were less consistent.
Overall, e-cigarette users showed no statistically significant increase in stroke risk (OR 1.05, 95% CI 0.91–1.19), and smoking-adjusted analyses were similarly non-significant.
However, among former smokers who currently use e-cigarettes, stroke odds were significantly higher at 73% above non-users (OR 1.73, 95% CI 1.30–2.15).
Among exclusive e-cigarette users who had never smoked combustible cigarettes, no significant association was observed for MI (OR 0.96) or stroke (OR 0.97). These estimates were based on limited data and may be affected by misclassification of smoking status.
Interpretation and implications
This systematic review suggests that e-cigarette use is associated with increased odds of myocardial infarction, particularly among peoples with a history of cigarette smoking.
Although exclusive vaping among never-smokers was not associated with statistically significant cardiovascular risk in this analysis, the elevated risk observed among former smokers raises concerns about the use of e-cigarettes as harm-reduction or transition tools.
Most included studies were cross-sectional, limiting causal inference, and substantial heterogeneity, publication bias, and residual confounding remain important limitations. The authors conclude that further high-quality longitudinal studies are required and that e-cigarettes should not be considered harmless from a cardiovascular perspective.
Study details
Are electronic cigarettes associated with the risk of myocardial infarction and stroke? A systematic review and meta-analysis.
Ruchika Gupta, Prashant Kumar Singh, Sagarika Rout, Lorena C Mariano, Chander Prakash Yadav & Shalini Singh.
Published in BMC Public Health on 11 December 2025
Abstract
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 summarising 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 randomised 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.
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