Electronic cigarettes may increase two separate risk factors for heart disease, a new study finds. The study was small. It looked at just 16 vapers and 18 people who neither smoked nor vaped. Still, the symptoms uncovered were “spot-on” for what has been seen in heart attack patients and those with heart disease and diabetes, says Holly Middlekauff.
She and her coauthors at the University of California, Los Angeles, shared their findings online February 1. They were published in JAMA Cardiology.
Just two or three patients can skew results in a study of this size, notes heart specialist John Ambrose. He works at the University of California, San Francisco and was not involved in the new research. Another issue concerns Ambrose: Some vapers in this study used to smoke cigarettes. That, too, he notes, could skew the data.
Still, he called the new findings interesting. And every new study may be important, he adds. After all, he notes, “the medical community just doesn’t have enough information” yet to fully understand vaping’s impacts on health.
What the study found
Adrenaline — also known as epinephrine — is a natural hormone. It’s best known for its role in the so-called “fight or flight” response. When released into the bloodstream, it increases the rate at which the heart pumps blood around the body. It also ups the breathing rate and can prepare muscles for exertion. People who constantly show high levels of this hormone face a high risk of heart disease. And in the new study, regular vapers had heartbeat patterns that indicated they had high levels of this hormone.
(Nicotine is the addictive substance in both tobacco and the flavored liquids that are vaporized in e-cigarettes. It, too, can boost adrenaline. So the researchers had made their subjects avoid vaping on test days.)
Middlekauff says the new data show that vapers’ hearts are in “flight or fight” mode all the time, not just as they vape.
Her team also found signs of increased cellular stress in regular vapers. The body produces oxidants, reactive molecules that can kill cells. This will get rid of damaged tissues and germs. But too much of these stressful oxidants can damage arteries or narrow them. Environmental conditions can also trigger this. For instance, some air pollutants produce oxidants.
Previous research had linked oxidant stress to e-cigarettes. The new study targeted where it might occur and how it might affect the heart, notes Aruni Bhatnagar. He works for the American Heart Association Tobacco Regulation and Addiction Center. It’s based at the University of Louisville in Kentucky.
This new study “adds to the case that there may be some residual harm associated with e-cigarettes,” he says. (Bhatnagar wrote an editorial on vaping and heart risks in the same issue of JAMA Cardiology.)
Recent studies have linked other health concerns to vaping. Some found high levels of inflammation in the lungs of experimental animals. Others showed e-cig vapors can lower the activity of many human genes linked to immunity and alter genes associated with mental health. And one demonstrated that the intense heating of the solvents in e-liquids by e-cigs creates toxic vapors.
For Middlekauff, the next step will be to nail down exactly what in e-cigarettes triggered the effects that her team turned up. Her group also wants to compare vaping’s heart effects to those caused by smoking.
“Electronic cigarettes aren’t harmless,” Middlekauff concludes. “They have real, measurable physiological effects. And these physiological effects — at least the couple that we found — have been associated with heart disease.”