Since we published the first study demonstrating that e-cigarette use was associated with higher odds of having had a heart attack, e-cigarette advocates have argued that this association was an artifact of current or former cigarette smoking or “reverse causation” due to smokers starting to use e-cigarettes after they had a heart attack. Now Talal Alzahrani has published “Electronic Cigarette Use and Myocardial Infarction” that shows that e-cigarette use is associated with having had a heart attack in never smokers.
As he explains:
Since we published the first study, which showed daily e-cigarette use is associated with myocardial infarction independent of the effects of tobacco smoking, several researchers have argued that the association between e-cigarette use and myocardial infarction could be biased by smokers who switched to e-cigarettes following having a myocardial infarction, even though smokers who developed myocardial infarction are less likely to use e-cigarettes following their myocardial infarction than subjects who did not have a myocardial infarction. The present study avoids any possible bias associated with tobacco smoking by examining the association between e-cigarette use and myocardial infarction in subjects who never smoked conventional cigarettes. The results of this study are consistent with biological studies, which showed that e-cigarette use is associated with endothelial dysfunction, oxidative stress, inflammation, and platelet activation. [emphasis added, citations deleted]
To get enough adult e-cigarette users who never smoked, Alzahrani combined data from the US National Health Interview Surveys from 2014 through 2021, which yielded 1237 never smoking e-cigarette users. After controlling for other risk factors for heart attack, he found that current e-cigarette users had 2.6 times the odds of having had a heart attack as non-e-cigarette users (95% CI 1.44-4.77) compared with never smokers who did not use e-cigarettes.
This is a higher risk estimate that earlier studies that included and controlled for smoking, suggesting that smoking is obscuring rather than inducing the association between e-cigarette use and heart attacks.
The fact that e-cigarette users were less likely to have other risk factors for heart attack (age, diabetes, hypertension, high cholesterol, or be overweight or obese) compared to never users makes the association between e-cigarette use among never smokers even more impressive. (E-cigarette users did tend to be male, which increases heart attack risk.) In any event, Alzahrani controlled for these factors.
This result, combined with earlier research (one of the many studies) reporting increased risk of respiratory disease in never smokers, shows that the disease risks associated with current and former smoking cannot explain the disease associations with e-cigarette use.
Here is the abstract:
BACKGROUND: Current electronic cigarettes (e-cigarettes) is associated with myocardial infarction, controlling whether the subjects smoke cigarettes. However, no studies have been conducted on subjects who never smoked cigarettes. This study aimed to determine the association between e-cigarette use and myocardial infarction among subjects who have never smoked cigarettes.
METHODS: The National Health Interview Survey (NHIS) data from 2014 to 2021 was used to evaluate the relationship between e-cigarette use and myocardial infarction in subjects who have never smoked cigarettes after adjusting for risk factors, including age, sex, diabetes, hypertension, hypercholesterolemia, and obesity/overweight, using logistic regression.
RESULTS: A total of 139,697 subjects were never users, and 1,237 subjects were current e-cigarette users. E-cigarette users were significantly younger than never users. E-cigarette users were less likely to be female (40% vs. 60%, p <0.01), or have diabetes (3% vs. 10%, p <0.01), have hypertension (11% vs. 32%, p <0.01), have hypercholesterolemia (8% vs. 27%, p <0.01), or be overweight or obese (56% vs. 65%, p <0.01) compared to never users. The current e-cigarette
users had a 2.6-fold increase in the odds of having a myocardial infarction (OR 2.62, 95% CI 1.44-4.77; p <0.01) after adjusting for sex, age, hypertension, diabetes, hypercholesterolemia, and obesity/overweight. Conclusions: This study suggests that current e-cigarette use increases the risks of cardiovascular disease, including myocardial infarction and stroke, in subjects who never smoked cigarettes. Further longitudinal studies are needed to confirm the results of this study.
The full citation is: Alzahrani T. Electronic Cigarette Use and Myocardial Infarction. Cureus. 2023 Nov 6;15(11):e48402. doi: 10.7759/cureus.48402. PMID: 38073929; PMCID: PMC10700683. In is available here.
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