E-cigarettes entered the market as consumer products without comprehensive toxicological testing,based on the assessment that they were 95% less harmful than traditional cigarettes. Further, consumer dvertising suggests that e-cigarettes are a good alternative to conventional combustible cigarettes and can serve as a gateway to quitting smoking.
However, hen considering damage to the endothelium and toxicity, e-cigarettes have a negative impact like that of conventional cigarettes. Moreover, switching to e-cigarettes often leads to dual use, said Stefan Andreas, MD, director of the Lungenfachklinik in Immenhausen, Germany, at the Congress of the German Respiratory Society and Intensive Care Medicine.
Subclinical Atherosclerosis
Because e-cigarettes have emerged relatively recently, long-term studies on their cardiac consequences are not yet available. Dr. Andreas explained that the impact on endothelial function is relevant for risk assessment. Endothelial function is a biomarker for early, subclinical atherosclerosis. “If endothelial function is impaired, the risk for heart attack and stroke is significantly increased 5-10 years later,” said Dr. Andreas.
The results of a crossover study showed reduced vascular elasticity after consuming both tobacco cigarettes and e-cigarettes. The study included 20 smokers, and endothelial function was measured using flow-mediated vasodilation.
Significant effects on the vessels were also found in a study of 31 participants who had never smoked. The study participants inhaled a nicotine-free aerosol from e-cigarettes. Before and after, parameters of endothelial function were examined using a 3.0-T MRI. After aerosol inhalation, the resistance index was 2.3% higher (P < .05), and flow-mediated vascular dilation was reduced by 34% (P < .001).
A recent review involving 372 participants from China showed that e-cigarettes lead to an increase in pulse wave velocity, with a difference of 3.08 (P < .001). “Pulse wave velocity is also a marker of endothelial function: The stiffer the vessels, the higher the pulse wave velocity,” said Dr. Andreas. The authors of the review concluded that “e-cigarettes should not be promoted as a healthier alternative to tobacco smoking.”
No Harmless Alternative
A recent review compared the effects of tobacco smoking and e-cigarettes. Although the toxic mixture in smoke is more complex, both e-cigarettes and tobacco cigarettes “impaired endothelial function to a similar extent,” they wrote. The authors attributed this finding to oxidative stress as the central mechanism.
“There is increasing evidence that e-cigarettes are not a harmless alternative to tobacco cigarettes,” wrote Thomas Münzel, MD, professor of cardiology at the University of Mainz and his team in their 2020 review, which examined studies in humans and animals. They provided an overview of the effects of tobacco/hookah smoking and e-cigarette vaping on endothelial function. They also pointed to emerging adverse effects on the proteome, transcriptome, epigenome, microbiome, and circadian clock.
Finally, a toxicological review of e-cigarettes also found alarmingly high levels of carcinogens and toxins that could have long-term effects on other organs, including the development of neurological symptoms, lung cancer, cardiovascular diseases, and cavities.
Dr. Andreas observed that even small amounts, such as those obtained through secondhand smoking, can be harmful. In 2007, Dr. Andreas and his colleagues showed that even low exposure to tobacco smoke can lead to a significant increase in cardiovascular events.