A small study published in the JAMA Cardiology medical journal found that regular e-cigarette use appears to be associated with shifts in cardiac sympathetic activity and and increased oxidative stress, mechanisms believed to increase the risk of cardiovascular disease. However, the many limitations of this research have prompted members of the scientific community to question its conclusion.
The study conducted by researchers at the University of California Los Angeles included 23 self-identified habitual users of e-cigarettes (used most days for at least one year) and 19 non-smokers/non-vapers between the ages of 21 and 45 years. Participants reported no known medical conditions, nor the use of any prescription medication.
In a controlled environment, scientists measured two mechanisms by which traditional smoking is believed to cause cardiovascular disease: shift in the cardiac sympathovagal balance toward sympathetic predominance as assessed by heart rate variability (HRV) and increased systemic oxidative stress and inflammation. To avoid the potential influence of other factors – circadian rhythm and menstrual cycle phases – participants were studied midday and women were studied during their early follicular phase. E-cigarette users were asked to abstain from vaping on the day of the study, to prevent the influence of nicotine.
After analyzing the results, researchers found that habitual e-cigarette users were more likely than non-smokers/non-vapers to have increased cardiac sympathetic activity (increased adrenaline levels in the heart) and increased oxidative stress. “In this study, habitual e-cigarette use was associated with a shift in cardiac autonomic balance toward sympathetic predominance and increased oxidative stress, both associated with increased cardiovascular risk,” the study conclusion reads.
“My patients need to know and the public needs to know that if you don’t already smoke tobacco cigarettes, you shouldn’t start smoking e-cigarettes because they’re not harmless,” lead author Holly Middlekauff, a cardiologist at the University of California, told The Verge. “They have real, measurable physiological effects and these physiological effects, at least the couple that we found, have been associated with heart disease.”
Middlekauff adds that the findings of the study are important because they show that the hearts of e-cigarette users are constantly in “fight or flight” mode, not just when they are vaping. The fight or flight response is our body’s automatic response to perceived attack, harm or threat to our survival, which prompts us to fight or flee. It is characterized by the the release of adrenaline into the bloodstream, which increases our heart rate and respiratory rate.
As is always the case with studies that put vaping and electronic cigarettes in a bad light, this research has already been picked up by the media as a scaremongering tool. However, the scientific community seems to be split on what this research actually shows.
“Studies like this give further confirmation that e-cigarettes are not harmless,” said European Society of Cardiology cardiovascular prevention spokesperson Professor Joep Perk. “If I was a minister of health I would put my efforts into public anti-smoking campaigns especially directed towards the younger generation, and not promote e-cigarettes as an alternative to smoking.”
“It is too large a step to say that these negative effects are proof that people are going to die early because they used e-cigarettes,” Perk adds. “To prove this you have to put people on e-cigarettes for 10 to 15 years and see how many die early – a study that will not be done for ethical reasons. The weakness of all studies in this field is that they are observational and small, and they look at indicators of vascular wall damage rather than incidence of cardiovascular disease or death.”
In his opinion, e-cigarettes could still be used to help people quit smoking, but they should be used with caution, and only after the traditional smoking cessation options have been exhausted.
Gordon Tomaselli, the chief of the cardiology division at Johns Hopkins University and a former American Heart Association president, also cautions people to not draw hasty conclusions based on this study, due to its clear limitations. The small number of participants is a big issue, as just two or three patients can skew results, especially since they were reporting their own habits, sometimes dishonestly (a number of participants were excluded from the study after claiming that they didn’t smoke tobacco cigarettes, when the levels of carbon dioxide in their blood tests showed otherwise).
Furthermore, Tomaselli emphasizes the fact that the findings of the study don’t actually connect e-cigarette use to heart disease, just that vaping affects bio-markers used by the medical community as risk factors. “These surrogate markers … are cautionary tales,” he says, “And I think warrant longer-term follow-ups.”
Curiously enough, the Middlekauff et al. study did not include a group of smokers, which would have surely offered interesting information on the effects of vaping compared to smoking, in terms of cardiovascular risk. “It would be very nice to know what the magnitude of the injury is,” said Aruni Bhatnagar, a professor of medicine at the University of Louisville, who studies oxidative stress. “We lack a scale.”
Prof. Bhatnagar makes good a point. The study tells us that regular e-cigarette use affects certain markers associated with risk of cardiovascular disease, but just how significant is the impact of vaping on cardiovascular functions, and, most importantly, how bad is it compared to smoking, the thing we already know is shortening the life of 50% of smokers.
The conclusion that electronic cigarettes are not harmless may mean everything when you are an anti-nicotine zealot who puts ideology above public health, but from a harm-reduction perspective, it means very little. If the point is to minimize the harm caused by smoking by adopting a less dangerous alternative, then a comparison to the effect of tobacco cigarettes may reveal that vaping is an important tool in tobacco harm reduction. Who ever claimed that e-cigarettes were harmless, anyway?
Lastly, the most significant limitation of this study, in my opinion, is that it does not take into consideration that most, if not all, of the electronic cigarette users analyzed were once tobacco smokers. Is it too much to assume that years of cigarette smoking could have altered their cardiovascular function, at least to some degree, thus influencing the results of this research. I don’t know, I’m not a scientist, but I definitely think it’s possible.
So before you decide to quit vaping and go back to smoking because they’re both just as bad, think for a moment. Don’t let the inconclusive findings of one study push you back to something that has already been proven extremely harmful to health. If you can quit e-cigarettes and stay nicotine-free, that’s definitely the best thing you can do, but if the alternative is going back to smoking, it’s just not worth it!