Are e-cigarettes less harmful than conventional cigarettes that contain tobacco? From a cardiovascular point of view, at least, new research answers with a resounding "no." In fact, says one study author, "e-cigs may confer as much and potentially even more harm to users" than traditional cigarettes.

In light of the recent lung injury outbreak that some researchers have linked to vaping products and electronic cigarettes, two new studies presented at the American Heart Association's Scientific Sessions 2019 in Philadelphia, PA, further highlight the potentially hazardous effects of e-cigarettes on health.

The two new studies examine the effect of e-cigarettes on cardiovascular health, more specifically. In this respect, there appears to be insufficient evidence to draw a firm conclusion.

However, the two new studies emphasize the possibility that e-cigarettes are just as, if not more harmful than regular cigarettes.

Dr. Sana Majid, a postdoctoral fellow in vascular biology at the Boston University School of Medicine in Massachusetts, is the lead author of the first study, which looked at cholesterol, triglycerides, and glucose levels in cigarette smokers.

Dr. Florian Rader, MS, medical director of the Human Physiology Laboratory and assistant director of the Non-Invasive Laboratory at the Cedars-Sinai Medical Center in Los Angeles, CA, led the second study, which looked at heart blood flow.

E-cigarettes and cholesterol

In the first study, Dr. Majid and team compared markers of cardiovascular health among healthy adults who smoked regular cigarettes, adults who used e-cigarettes, healthy adults who did not smoke, and adults who smoked both e-cigarettes and conventional cigarettes.

The 476 study participants were between 21 and 45 years old; they had no history of cardiovascular disease and were not taking any daily medication.The researchers accounted for potential confounders, such as age, race, and sex, in their analysis.

They also adjusted their analysis to examine non-smokers, sole e-cigarette or traditional cigarette users, or dual users.

The analysis revealed that people who used only e-cigarettes had higher levels of low-density lipoprotein (LDL) cholesterol, or "bad" cholesterol, and lower levels of total cholesterol than non-smokers.

High-density lipoprotein (HDL), or "good" cholesterol, was lower in people who smoked both traditional cigarettes and e-cigarettes.

"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."

—Dr. Sana Majid

"The best option is to use FDA-approved methods to aid in smoking cessation, along with behavioral counseling," Dr. Majid adds.

Possibly even more harmful to users

In the second study, Dr. Rader and his colleagues examined the heart blood flow of 19 adults aged between 24 and 32 before and after smoking traditional cigarettes or e-cigarettes.

More specifically, they looked at the participants' coronary vascular function using myocardial contrast echocardiography (MCE) scans.

MCE scans use gas-filled microbubbles that travel inside the vascular space, just like red blood cells, to assess myocardial microcirculation.

The researchers used an MCE scan when the participants were resting and after they had simulated physiological stress with a handgrip exercise test.

Dr. Rader reports, "In smokers who use traditional cigarettes, blood flow increased modestly after traditional cigarette inhalation and then decreased with subsequent stress. However, in smokers who use e-cigs, blood flow decreased after both inhalation at rest and after handgrip stress."

Study co-author Dr. Susan Cheng, MMSc, MPH, who is a director of Public Health Research at Cedars-Sinai Medical Center, says, "We were surprised by our observation of the heart's blood flow being reduced at rest, even in the absence of stress, following inhalation from the e-cigarette."

"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."

—Dr. Susan Cheng