Cardiovascular effects of switching from tobacco cigarettes to electronic cigarettes, this time showing benefit

Jacob George and colleagues recently published “Cardiovascular Effects of Switching From Tobacco Cigarettes to Electronic Cigarettes” in Journal of the American College of Cardiology.  This nicely-done study measured changes in blood vessel function in cigarette smokers before and a month after they switched from cigarettes to e-cigarettes and found that vascular function improved after switching.

A particularly interesting result is that the improvement was seen in women but not men.  There are gender differences in heart disease mechanisms and risks (especially before menopause).  This paper highlights the importance of considering gender effects when assessing effects of e-cigarettes on the cardiovascular system.

Like other studies of the effects of e-cigs on vascular function, the effect was independent of nicotine.

This paper does differ from most of the literature, which shows that e-cigs have similar effects on blood vessels as cigarettes (some recent examples are here), but, as noted above, this study is well done and the results contribute to the overall evidence base on ecigs and cardiovascular function.

Here is the abstract:

Background E-cigarette (EC) use is increasing exponentially worldwide. The early cardiovascular effects of switching from tobacco cigarettes (TC) to EC in chronic smokers is unknown. Meta-analysis of flow-mediated dilation (FMD) studies indicate 13% lower pooled, adjusted relative risks of cardiovascular events with every 1% improvement in FMD.

Objectives This study sought to determine the early vascular impact of switching from TC to EC in chronic smokers.

Methods The authors conducted a prospective, randomized control trial with a parallel nonrandomized preference cohort and blinded endpoint of smokers ≥18 years of age who had smoked ≥15 cigarettes/day for ≥2 years and were free from established cardiovascular disease. Participants were randomized to EC with nicotine or EC without nicotine for 1 month. Those unwilling to quit continued with TC in a parallel preference arm. A propensity score analysis was done to adjust for differences between the randomized and preference arms. Vascular function was assessed by FMD and pulse wave velocity. Compliance with EC was measured by carbon monoxide levels.

Results Within 1 month of switching from TC to EC, there was a significant improvement in endothelial function (linear trend β = 0.73%; 95% confidence interval [CI]: 0.41 to 1.05; p < 0.0001; TC vs. EC combined: 1.49%; 95% CI: 0.93 to 2.04; p < 0.0001) and vascular stiffness (−0.529 m/s; 95% CI: −0.946 to −0.112; p = 0.014). Females benefited from switching more than males did in every between-group comparison. Those who complied best with EC switch demonstrated the largest improvement. There was no difference in vascular effects between EC with and without nicotine within the study time frame.

Conclusions TC smokers, particularly females, demonstrate significant improvement in vascular health within 1 month of switching from TC to EC. Switching from TC to EC may be considered a harms reduction measure. (Vascular Effects of Regular Cigarettes Versus Electronic Cigarette Use [VESUVIUS]; NCT02878421; ISRCTN59133298)

The full citation is Jacob George, Muhammad Hussain, Thenmalar Vadiveloo, Sheila Ireland, Pippa Hopkinson, Allan D. Struthers, Peter T. Donnan, Faisel Khan, Chim C. Lang.  Cardiovascular Effects of Switching From Tobacco Cigarettes to Electronic Cigarettes.  J Am Coll Cardiol. 2019 Nov 15. Epublished DOI:10.1016/j.jacc.2019.09.067.  It is available here.