Cardiac adrenaline boost from e-cigarettes tied to nicotine

Nicotine in electronic cigarettes boosts the cardiac adrenaline levels of users, which could put them at increased risk for heart disease, according to a new study in the Journal of the American Heart Association.

Researchers analyzed the heart rate variability in 33 healthy nonsmokers after one e-cigarette with nicotine, one e-cigarette without nicotine and one sham device. There was a four-week washout between exposures.

Only the e-cigarette with nicotine was associated with increased activity of the sympathetic nervous system (SNS), which stimulates the body’s fight or flight response. Perpetually elevated activity of the SNS contributes to increased cardiac risk.

“While it’s reassuring that the non-nicotine components do not have an obvious effect on adrenaline levels to the heart, these findings challenge the concept that inhaled nicotine is benign, or safe,” senior study author Holly R. Middlekauff, MD, professor of medicine and physiology at UCLA, said in a press release.

“Our study showed that acute electronic cigarette use with nicotine increases cardiac adrenaline levels. And it’s in the same pattern that is associated with increased cardiac risk in patients who have known cardiac disease, and even in patients without known cardiac disease. I think that just seeing this pattern at all is very concerning and it would hopefully discourage nonsmokers from taking up electronic cigarettes.”

Volunteers’ heart rates increased by an average of seven beats per minute after smoking the e-cigarette with nicotine. There were no significant heart rate changes after the other two exposures.

None of the devices was found to increase oxidative stress with a single use. However, Middlekauff and colleagues noted further studies are needed to assess e-cigarettes’ relationship to oxidative stress, a key contributor to the development of atherosclerosis.