Electronic cigarettes (e-cigarettes) are often promoted as an alternative to smoking. A study published in JAMA Cardiology has added to growing evidence that e-cigarettes are not harmless.
"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," he continued. "There are studies also showing that people that start with e-cigarettes have a tendency to become persistent tobacco cigarette smokers as well."
The current study included 23 habitual e-cigarette users (used most days for at least one year) and 19 non-users between the ages of 21 and 45 years. It found that habitual e-cigarette users were more likely than non-users to have increased cardiac sympathetic activity (increased adrenaline levels in the heart) and increased oxidative stress - known mechanisms by which tobacco cigarettes increase cardiovascular risk.
The authors said the findings "have critical implications for the long-term cardiac risks associated with habitual e-cigarette use" and "mandate a re-examination of aerosolized nicotine and its metabolites". They added that causality could not be confirmed on the basis of this single, small study, and that further research into the potential adverse cardiovascular health effects of e-cigarettes is warranted.
"Nicotine stimulates the central nervous system, so it's not at all surprising that people continuously taking nicotine get this sympathetic stimulation," said Professor Perk. "This then might lead to irregular heartbeat and raised blood pressure, and probably has long-term deleterious effects on the blood vessel walls."
"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," he continued. "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."
Professor Perk said that, even after this study, e-cigarettes could still be used to help people stop smoking tobacco cigarettes, but they should be used with caution and other methods should preferably be tried first.
He said: "E-cigarettes are one of the tools we have in nicotine replacement therapy but as clinicians we should be cautious of putting people on large amounts of central nervous system stimulant drugs. Other smoking cessation schemes, such as chewing gum or patches, always include the decision to taper off use and eventually stop. This is not in general the case with e-cigarettes, which tend to be seen as a replacement and not a weaning off nicotine addiction. In fact they prolong the addiction."
"This is an area where we need more knowledge," continued Professor Perk. "The more data we collect, the more it seems that nicotine replacement strategies that taper off and ultimately end nicotine use are the way to go."
"At the end of the day the best thing is simply to prevent people ever getting into the vicinity of nicotine," he concluded.