Vaping’s Risks to CV Health Not Yet Fully Known: AHA

Uptake of e-cigarettes and other vaping devices has been swift in recent years, partly due to the perception that the products are less harmful than traditional cigarettes, but as a new scientific statement from the American Heart Association (AHA) makes clear, there’s much left to learn about whether this is in fact true.

“Because of their more limited ingredients and the absence of combustion, e-cigarettes and vaping products are often touted as safer alternative and potential tobacco-cessation products,” Jason J. Rose, MD, MBA (University of Maryland School of Medicine, Baltimore), and colleagues note in their paper, published online today in Circulation.

Yet this doesn’t mean they’re without harm: in 2019, for instance, e-cigarette or vaping product use-associated lung injury (EVALI) led to more than 2,800 hospitalizations in the United States.

Rose told TCTMD that, as a pulmonary critical care specialist with an interest in carbon monoxide poisoning, the EVALI outbreak is what first drew him into this topic. “Come to find out vaping products actually, particularly the flavored vaping products, oftentimes will have some chemicals that are known toxins,” he said.

The devices, which fall under the umbrella term of electronic nicotine delivery systems (ENDS), use heat or atomization of a liquid—typically a combination of a humectant, flavoring, and nicotine, but sometimes THC or other substances—to generate vapor without producing smoke. They first emerged in China in the early 2000s and arrived in the United States later that decade. Since 2010, amid surging use, ENDS have been regulated by the Food and Drug Administration “as tobacco products and thus do not undergo the premarket animal and human safety studies required of a drug product or medical device,” the AHA statement points out.

By 2019, more than a quarter of US high school students who responded to the NYTS (National Youth Tobacco Survey) said they currently used e-cigarettes, as compared with 5.8% who smoked conventional cigarettes, the AHA statement specifies. Among adults, most ENDS users are current or former cigarette smokers.

The health ramifications of e-cigarettes and vaping flew under the radar for many years, and though public awareness is growing, said Rose, it took a step backwards a little during the COVID-19 pandemic, while other respiratory risks drew more attention. Even so, there’s been progress when it comes to regulatory efforts, such as the crackdown on menthol-flavored e-cigarettes and the increase in the federal minimum age, to 21 years old, for the sale of tobacco products, he added. “The problem, though, is that it's a very innovative industry and . . . certain [aspects] of vaping devices aren't covered by all regulatory standards.” For instance, consumers can buy their own custom flavor mixes, something that’s hard for regulators to track.

The 26-page document provides an overview of the history of e-cigarettes and vaping; their rising use; potential chronic and acute health effects; whether there is a role for these products in cigarette cessation; the public health perspective; a look into how e-cigarettes are regulated and marketed; and directions for future research.

Waiting 30 years isn't going to be acceptable, especially if you look at the rates of young people who are vaping. Jason J. Rose

Importantly, ENDS are diverse and continue to change, making it all the more difficult to draw firm conclusions about safety.

The vapor “generated from different device types and products results in differential effects on measures of endothelial and pulmonary epithelial cell toxicity. The toxicological differences are likely due to differences in product characteristics such as nicotine levels and flavoring additives,” the co-authors note. Whether or not nicotine is present—and it’s not always—"many ENDS product constituents, including flavoring additives, hygroscopic carriers such as propylene glycol and glycerol, and metals (from the heating coil), have been shown to induce cardiopulmonary toxicity in animal and in vitro studies.”

Data on the cardiovascular effects of e-cigarettes and other vaping products are mostly limited to younger adults and mostly capture short-term risk. Even less is known about longer-term, chronic impacts, since ENDS have only existed for two decades.

“E-cigarettes and vaping products haven't been on the market that long. . . . I think it's really hard to make an assessment on long-term safety when you don't have that data,” said Rose, adding, “You can’t just assume it’s safe.”

In the interim, as the evidence accrues, molecular and animal studies can provide clues about the long-term ramifications, he said. “Waiting 30 years isn't going to be acceptable, especially if you look at the rates of young people who are vaping.”

For many current smokers, e-cigarettes hold appeal as a way to quit smoking, or at least to cut back. There are some studies to support that idea, even a randomized trial, but data are less convincing for people who vape on top of their existing smoking habit.

“To be clear, [these products] are not FDA-approved as a therapeutic for tobacco cessation,” Rose said, stressing that without a better understanding of the trade-offs involved in this approach, it’s better for smokers “to get off of all inhaled products.” Moreover, he added, any legitimacy ascribed to ENDS could have an unintended effect by inspiring more young people who wouldn’t have otherwise been cigarette smokers to pick up a vape pen.

Rose said that, in writing the AHA scientific statement, their goal was simple: to raise awareness by summing up what’s known so far about ENDS. “We tried to look at things very objectively as far as what's out there, what's not out there,” he said, with an eye toward approaches for dealing with the current uncertainty.