E-cigarettes aren’t harmless. Although viewed as a healthier alternative, the study finds that e-cigarette smoking impacts heart health similar to the smoking of traditional cigarettes.

Several heart disease risk factors — cholesterol, triglycerides, and glucose levels, as well as decreased blood flow in the heart — are negatively impacted by e-cigarette smoke. The findings will be presented at the American Heart Association’s Scientific Sessions 2019, later this month.

Not harmless by far

“There is no long-term safety data on e-cigarettes. However, there are decades of data for the safety of other nicotine replacement therapies,” explains Rose Marie Robertson, M.D., FAHA, the American Heart Association’s deputy chief science and medical officer.

The American Heart Association (AHA) recommends the use of FDA-approved smoking cessation aids, which are proven safe and effective. Robertson says that people often choose e-cigarettes as an alternative to quitting (as it is perceived as being safer than traditional tobacco), or as a temporary solution while working to quit altogether. In the latter case, however, she warns that people should also plan how to subsequently stop using e-cigarettes. There is a striking lack of data on the long-term safety of such devices, and growing concerns over the physiological effects caused by the chemical cocktails therein.

One study used in this report — the Cardiovascular Injury due to Tobacco Use (CITU) Study — compared cholesterol, triglycerides, and glucose levels in healthy adult nonsmokers, e-cigarette smokers, traditional cigarette smokers, and dual smokers (who use both traditional and e-cigarettes). Participants were aged 21-45, didn’t have any preexisting cardiovascular disease, and took no relevant medication. Out of the total of 467 participants, 94 were non-smokers, 52 were dual smokers, 45 were e-cigarette smokers, and 285 were traditional cigarette smokers.

After adjusting for age, race, and sex, the team reports that total cholesterol was lower for e-cig smokers, but their low-density lipoprotein (LDL, ‘bad’ cholesterol) levels were higher, compared to nonsmokers. High-density lipoprotein (HDL, ‘good’ cholesterol) was lower in dual smokers.

“Although primary care providers and patients may think that the use of e-cigarettes by cigarette smokers makes heart health sense, our study shows e-cigarette use is also related to differences in cholesterol levels. The best option is to use FDA-approved methods to aid in smoking cessation, along with behavioral counseling,” said study author Sana Majid, M.D., a postdoctoral fellow in vascular biology at the Boston University School of Medicine.

Another study looked at heart blood flow as a measure of coronary vascular function in 19 young adult smokers (ages 24-32) immediately before and after smoking either e-cigarettes or traditional cigarettes. The study looked at this metric both at rest and after performing a handgrip exercise (meant to simulate physiological stress).

For smokers of traditional cigarettes, the team saw a “modest” increase in blood flow after cigarette inhalation, which decreased with subsequent stress. E-cig smokers, however, saw blood flow decrease both at rest and after the handgrip exercises. All in all, e-cigarette use seems to be associated with coronary vascular dysfunction to a greater degree than seen in traditional cigarettes.

“These results indicate that e-cig use is associated with persistent coronary vascular dysfunction at rest, even in the absence of physiologic stress,” said study author Florian Rader, medical director of the Human Physiology Laboratory and assistant director of the Non-Invasive Laboratory, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles.

“Providers counseling patients on the use of nicotine products will want to consider the possibility that e-cigs may confer as much and potentially even more harm to users and especially patients at risk for vascular disease,” added study co-author Susan Cheng, director of Public Health Research at the Cedars-Sinai Medical Center.

The studies were funded by The National Heart, Lung, and Blood Institute and the FDA Center for Tobacco Products, and The California State Tobacco-related Disease Research Program High Impact Pilot Research Award. The American Heart Association Tobacco Center for Regulatory Science provided research materials for the first study.

The findings will be presented at the American Heart Association’s Scientific Sessions 2019 conference, November 16-18 in Philadelphia, USA (sessions Mo3106, Sa3199).