E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice.

Introduction:
This article reports on a study examining the effects of e-cigarette aerosols on cardiac electrophysiology in mice. The study found that e-cigarette aerosols can disturb cardiac conduction and induce bradycardia, bradyarrhythmias, and elevations in heart rate variability during inhalation exposure. The study also found that the pro-arrhythmic effects of solvent aerosols on ventricular repolarization and heart rate variability depend partly on parasympathetic modulation, while ventricular arrhythmias positively associate with early repolarization dependent on the presence of nicotine.

Key Points:

* The study used mice and exposed them to e-cigarette aerosols, mainstream cigarette smoke, acrolein, and aerosols generated by flavored e-cigs.
* E-cigarette aerosols induced arrhythmia, impaired ventricular repolarization, and altered several processes subject to autonomic modulation, including heart rate, supraventricular conduction, and hRV, consistent with autonomic imbalance.
* Exposure to e-cig aerosols increased the frequency of ventricular tachyarrhythmias in both male and female mice.
* Menthol-containing e-liquids displayed unique cardiotoxicity, with exposure to menthol-containing aerosols associated with increased VPBs and a 12-min aVRT episode in one male.
* The study found that e-cig solvent-induced bradyarrhythmias, bradycardia, and hRV changes were more pronounced in male than in female mice.
* The study also found that acrolein and low-nicotine sources of acrolein, including VG e-liquids and 1R5F, caused J depression and did not increase VPBs.
* The study found that nicotine promotes ventricular arrhythmia through ischemic effects.

Main Message:
The study suggests that e-cigarette use could increase CVD risk by inducing autonomic imbalance and cardiac arrhythmias, and that the magnitude and profile of responses may depend on chemicals in the e-liquids, such as nicotine, solvents, and flavors. The study also highlights the potential cardiotoxicity of menthol-containing e-cigarettes, which may be due to either their pharmacologic effects or their propensity to generate higher levels of aldehydes. The study's findings underscore the importance of further research on the short- and long-term cardiac effects of e-cigarette constituents, including nicotine, acrolein, PG, and menthol, both by themselves and in mixtures.

Carll aP, arab C, Salatini R, et al. E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice. Nature communications. 2022;13(1):6088. doi:10.1038/s41467-022-33203-1