The Cardiovascular Impact of Electronic Cigarettes Examined at AHA

Holly Middlekauff, MD

While electronic cigarettes are becoming increasingly popular with a younger demographic over traditional tobacco cigarettes, there could be hidden cardiovascular dangers lurking.

During the American Heart Association (AHA) 2019 Scientific Sessions in Philadelphia, Holly Middlekauff, MD, UCLA Health, presented new data about the cardiovascular risk of e-cigarettes.

“With the introduction of electronic cigarettes, we have to ask ourselves how safe is this inhaled nicotine,” Middlekauff said. “Does electronic cigarette use increase cardiovascular risk? The honest answer is we don't know so we’ll have to depend on our biomarkers.”

Middlekauff looked at sympathetic activation as an important biomarker, citing a recent study looking at the biomarker measured by heart rate variability.

In the study, the group that used e-cigarettes had decreased vagal activity and increased sympathetic nerve activity.

While this study included healthy, younger participants, the same pattern of heart rate variability is often seen in populations at an increased risk for adverse cardiovascular events.

However, testing this further, investigators found that only e-cigarettes with nicotine caused this same pattern of variables.

“I think that the more interesting news here is not that nicotine increases sympathetic nerve activity, but that non-combusted components or constituents do not,” Middlekauff said.

Next, they tested a nicotine inhaler, a clean source of inhaled nicotine.

“I'll tell you the levels of nicotine achieved after 30 minutes of using the nicotine inhaler for almost non-detectable, there was almost no bumps, so this is a promising pharmaceutical cessation device, but it wasn't successful in achieving plasma nicotine levels,” she said. “We did find is that the group that use electronic cigarettes with nicotine had an increase in systolic blood pressure, diastolic blood pressure, and heart rate.

She explained the main differences between nicotine replacement therapies and electronic cigarettes.

“Electronic cigarettes deliver nicotine inhaled aerosol that's inhaled into the fragile lung tissue, which may be more vulnerable to health effects,” Middlekauff said. “And also, nicotine electronic cigarettes are used for pleasure, and they may be a lifelong habit, unlike nicotine replacement therapies which we use for a matter of weeks.”

While nicotine replacement therapies increase the risk of palpitations, tachycardia, and atrial fibrillation, there is no evidence that says this practice increases the risk of major adverse cardiac events.

Middlekauff explained that this is true even for high risk patients recovering from a heart attack.

She also presented data on the cardiovascular risk linked to other forms of tobacco intake.

For example, smokeless tobacco confers a modest risk for fatal myocardial infarction, with a relative risk of 1.13.

Middlekauff said the majority of people believe that electronic cigarettes are safer than tobacco cigarettes.

According to Middlekauff, there are 7000 constituents in tobacco cigarettes, including 70 known carcinogens.

In a cross-sectional study of 5 different individuals looking at the level of carcinogens founds in the urine and saliva, investigators found carcinogen levels in the electronic cigarette group is vastly lower than cigarette users and nicotine replacement therapy groups.

Overall, Middlekauff said e-cigarettes may be less harmful than tobacco cigarettes, but she would not call them harmless.