Electronic cigarettes and cardiovascular health: what do we know so far?

Introduction:
This article review discusses the potential cardiovascular health effects of electronic cigarette (EC) use. While ECs are generally believed to be safer than traditional cigarettes, there are many uncertainties regarding their overall cardiovascular health impact. This review aims to summarize the current knowledge on the components of EC smoke and the potential mechanisms of cardiovascular injury caused by EC use.

Key Points:

* ECs are composed of a battery that heats a flavored liquid typically containing nicotine, producing an aerosol that the user inhales.
* EC emissions are free of harmful carbon monoxide and almost all carcinogens found in traditional cigarette smoke.
* Nicotine is the most biologically active agent in EC emissions, while nonnicotine toxicants are present in much lower concentrations.
* The adverse cardiovascular effects of traditional cigarettes are caused by increased oxidative stress, promotion of a proinflammatory state, and catecholamine release, leading to ischemia, arrhythmias, and sudden death.
* Nicotine-replacement therapy (NRT) studies have shown no increased risk of serious cardiovascular events, and NRTs can aid in smoking cessation.
* Smokeless tobacco (ST) studies suggest an elevated cardiovascular risk, but not as high as with traditional cigarettes.
* EC emissions contain nicotine, solvents, flavorings, free radicals, particulate matter, and metals, but their cardiovascular risks are not well defined.
* EC use has been associated with increased in flammation and oxidative stress, but these effects appear to be less pronounced than with traditional cigarettes.
* The available data are concerning for adverse vascular effects of acute EC use, possibly due to nicotine in EC emissions.
* Limited data suggest that acute EC use increases platelet aggregation, a risk factor for adverse cardiovascular events.
* Few studies have investigated long-term EC effects on hemodynamics, and the hemodynamic effects of ECs and traditional cigarettes are small and of unclear clinical significance.
* The majority of EC studies measured only acute, transient changes in blood pressure and heart rate, with limited long-term data.
* a single study found no change in left ventricular function after EC use, but changes in diastolic function after just one traditional cigarette.
* EC use in chronic users has been associated with the same adverse heart rate variability profile as traditional cigarette users, and nicotine in EC emissions contributes to acute abnormalities in heart rate variability.
* a large cross-sectional study reported increased risk (OR 1.79) of myocardial infarction in daily EC users, but did not delineate the temporal relationship between EC use and myocardial infarction.

Main Message:
The review highlights the need for further research to determine the long-term cardiovascular risks associated with EC use. While ECs may be less harmful than traditional cigarettes, they are not harmless, and their adverse effects on cardiovascular biomarkers, such as increased oxidative stress, in flammation, platelet aggregation, poor vascular health, and sympathetic activation, are concerning. Moreover, the rapid increase in EC use among youth necessitates more aggressive regulation to curb this trend and protect the health of young people.

MacDonald, andrea, and holly R. Middlekauff. “Electronic Cigarettes and Cardiovascular health: What Do We Know so Far?” Vascular health and Risk Management Volume 15 (June 2019): 159–74. https://doi.org/10.2147/VhRM.S175970.