E-cigarettes and waterpipe smoking appeared harmful for the vasculature in what limited evidence there is, according to a review of the literature.
Although studies linking cardiovascular ills to these products are limited and controversial, animal data do suggest a similar extent of endothelial dysfunction compared with traditional tobacco cigarettes, according to a group led by Thomas Münzel, MD, of the University Medical Center of Johannes Gutenberg-University Mainz, Germany.
The worsening of endothelial function — pointing to subclinical atherosclerosis — may be related to the interplay of toxic compounds, oxidative stress, and inflammation, the authors wrote in a review published online in European Heart Journal.
Epigenetic or circadian processes may also play a role, as activation of the mitochondrial adaptor protein p66Shc can provoke mitochondrial dysfunction and oxidative stress.
Recent years have brought a trend of decreasing cigarette smoking, though the rise of vaping and other smoking has been a source of worry for public health officials. E-cigarette or vaping-associated lung injury (EVALI) has been around reportedly as early as 2017 and has been responsible for the hospitalization of thousands and the death of several dozen people in the U.S.
“In general, the increased use of e-cigarettes and waterpipe is concerning and as recently recommended broader tobacco control efforts by raising tobacco taxes, adopting smoke-free laws, conducting mass media campaigns, and restricting tobacco marketing should be implemented for better health protection of the general population,” Münzel’s group concluded.
From various studies, the reviewers compiled estimates of long-term cardiovascular risk related to smoking and vaping, including:
- Cigarettes and stroke: OR 1.61, 95% CI 1.34-1.93 (strong level of evidence)
- Waterpipes and stroke: OR 4.35, 95% CI 1.54-12.27 (medium level of evidence)
- E-cigarettes and stroke: OR 0.69, 95% CI 0.34-1.42 (good level of evidence)
- Cigarettes and coronary artery disease (CAD): RR 2.34, 95% CI 1.96-2.79 (strong level of evidence)
- Waterpipes and CAD: OR 2.94, 95% CI 1.04-8.33 (good level of evidence)
- E-cigarettes and CAD: OR 1.89, 95% CI 1.01-3.53 (good level of evidence)
“Taken together, there is no doubt tobacco cigarette smoke has severe cardiovascular side effects leading to endothelial dysfunction, increased oxidative stress, and increased cardiovascular morbidity and mortality. There is also evidence that e-cigarette vapour is less toxic than tobacco smoke,” according to Münzel’s team.
“Nevertheless, acute e-cigarette smoking increases blood pressure, causes endothelial dysfunction and increases vascular and cerebral oxidative stress,” they cited from human and animal studies.
Similarly, waterpipe smoking “cannot be considered a healthy alternative” given that it was also associated with cardiovascular side effects, endothelial dysfunction, oxidative stress, and arterial hypertension, the authors said. “The greater smoke volumes expelled from waterpipe sessions may lead to even higher exposure to toxicants as compared to tobacco cigarette smoking,” they added.
Münzel and colleagues noted that questions remain regarding the long-term effects of e-cigarette and waterpipe smoking and secondhand smoke exposure. “There is no doubt, however, that smoking cessation is and will remain the most powerful approach to prevent smoking-induced cardiovascular and respiratory disease.”
Smoking and vaping cessation may be particularly important now during the COVID-19 pandemic, given that these activities may make patients more susceptible to severe symptoms, according to the authors, who noted that the SARS-CoV-2 virus infects the host through ACE2 receptors, which are expressed in endothelial cells and major organs.
Münzel disclosed research support from Foundation Heart of Mainz and the Boehringer Ingelheim Foundation.