A domestic study found that among smokers who underwent stent procedures for coronary artery disease, those who quit cigarettes and used e-cigarettes had a lower rate of major adverse cardiovascular events (MACE; all-cause death, spontaneous myocardial infarction, and repeat revascularization as a composite endpoint) than those who continued smoking cigarettes.
However, this does not mean that switching to e-cigarettes is more beneficial for cardiovascular health than quitting. The researchers emphasized that completely stopping the use of tobacco products is the best approach.
A team led by Professor Choi Gi-hong of the Division of Cardiology at Samsung Medical Center used National Health Insurance Service data to analyze 17,973 adult smokers who underwent percutaneous coronary intervention (PCI) from 2018 to 2021, and published the results last year in the European Heart Journal.
The researchers divided patients into three groups based on smoking behavior after PCI. The group that continued smoking cigarettes was the largest, with 8,951 people (49.8%). The quitting group numbered 7,328 (40.8%), and the e-cigarette switching group numbered 1,694 (9.4%). The average age of all participants was 60.4, and 97.1% were men.
The researchers followed the patients for an average of 2.4 years to assess MACE occurrence.
As a result, the cumulative incidence of MACE was 17.0% in the continued-cigarette group, 13.4% in the quitting group, and 10.8% in the e-cigarette switching group. On simple comparison, the e-cigarette switching group had the fewest MACEs.
However, the e-cigarette switching group was relatively younger and had a lower burden of comorbidities than the continued-cigarette or quitting groups, making it difficult to interpret the results based on simple comparisons. The researchers therefore conducted additional analyses adjusting for multiple factors, including age, sex, preexisting conditions, and smoking amount.
After adjustment, compared with the continued-cigarette group, the e-cigarette switching group had an 18% lower MACE incidence, and the quitting group had a 13% lower risk. However, the difference in MACE risk between the e-cigarette switching and quitting groups was not statistically significant.
While this shows an association that those who switched to e-cigarettes experienced fewer major cardiovascular events than those who continued smoking cigarettes, it cannot establish causality because it is a retrospective observational study.
It also does not mean that e-cigarettes are better for heart health than quitting or that they have the same effect as quitting.
Differences also appeared within the e-cigarette switching group depending on whether cigarette use was completely stopped. Of the 1,694 people in the e-cigarette switching group, 909 were in the complete-switch group who quit cigarettes and used only e-cigarettes, and 785 were in the dual-use group who used both cigarettes and e-cigarettes.
The cumulative incidence of MACE was 9.6% in the complete-switch group, lower than 12.2% in the dual-use group. Even after adjusting for various factors such as age, sex, and comorbidities, the complete-switch group had a 29% lower MACE risk than the dual-use group. The dual-use group continued to smoke an average of 6.4 cigarettes per day after PCI.
Based on these results, the researchers emphasized that for patients who have undergone stent procedures, completely stopping the use of tobacco products is the best lifestyle change.
Beyond being a retrospective observational study, this research has several limitations. First, smoking habits were identified through surveys, which can introduce recall bias. Smoking behavior may also have changed after the health checkups, so actual behavior during follow-up may not have been accurately captured.
Differences by type of e-cigarette were not analyzed. It was also not possible to determine what cessation treatments the quitting group received. Because most participants were men, the findings may not directly apply to women.
The World Health Organization (WHO) recommends prioritizing proven smoking-cessation methods such as counseling or nicotine replacement therapy rather than using e-cigarettes as harm reduction products.
The researchers said, "Further studies are needed to understand the long-term effects of e-cigarette use on cardiovascular outcomes."
References
European Heart Journal (2025), DOI: https://doi.org/10.1093/eurheartj/ehae705