Smokers who received smoking cessation counseling and used electronic cigarettes (e-cigarettes) containing nicotine were more than twice as likely to successfully quit smoking compared to those who received counseling but did not use e-cigarettes, in a clinical trial presented at the American College of Cardiology's Annual Scientific Session Together with World Congress of Cardiology (ACC.20/WCC). Researchers cautioned, however, that the health effects of e-cigarettes are unknown, and they should not be used for any purpose other than smoking cessation.

At 12 weeks, 21.9% of participants given nicotine-containing e-cigarettes had quit smoking, 17.3% of participants given non-nicotine e-cigarettes had quit and 9.1% of participants given only counseling had quit. Overall, those using nicotine-containing e-cigarettes were 2.4 times more likely to quit than those who did not vape at all.

"These findings show that nicotine e-cigarettes are effective for smoking cessation in the short term," said Mark J. Eisenberg, MD, MPH, a cardiologist at the Jewish General Hospital, professor of medicine at McGill University and the study's lead author. "Vaping with counseling is more effective than counseling alone, although it's not a magic bullet for smoking cessation."

Vaping has rapidly become more popular in recent years. Eisenberg said that there is evidence that some e-cigarette users try vaping to cut down on smoking, though only a few clinical trials have assessed the use of e-cigarettes as a smoking cessation tool, with somewhat mixed results. Further research is needed to elucidate potential health impacts of vaping, but Eisenberg said that they should be avoided by youth and anyone who does not smoke.

The new trial was designed to reflect the real-world conditions lifelong smokers face when attempting to quit. Researchers enrolled 376 participants at 17 sites in Canada. Participants were an average of 53 years old, had smoked for an average of 35 years and smoked an average of 21 cigarettes a day before the study. All participants were motivated to quit. Ninety-one percent had previously attempted to quit but failed, and the majority had previously tried smoking cessation medications or behavioral therapy without success.

One-third of the participants were assigned to receive e-cigarettes containing nicotine, one-third received e-cigarettes without nicotine and one-third did not receive an e-cigarette. All participants received about 100 minutes of counseling over the course of the 12 weeks that included guidance on quitting smoking. Those receiving e-cigarettes were instructed to vape as much as they felt they needed.

Participants reported their progress via three phone calls and two clinic visits during the 12-week treatment period. At clinic visits, participants underwent a breath test for carbon monoxide to verify whether or not they had smoked. At 12 weeks, those who reported not smoking a cigarette (even one puff) in the past week, and passed the breath test, were counted as having quit. For those who did not quit, researchers considered whether or not participants had reduced the total number of cigarettes smoked per day compared to the number they were smoking at the start of the study.

Eisenberg said that the quit rates among e-cigarette users were relatively high in the broader context of smoking cessation research, especially given that participants were heavy smokers who had used tobacco for years.

"While these are not clinical outcomes like death or lung cancer rates, the results are still quite impressive," he said.

Compared to baseline smoking rates of 21 cigarettes per day, participants who received nicotine e-cigarettes reduced their daily cigarette consumption by 13 cigarettes per day compared to 11 among participants receiving non-nicotine e-cigarettes and seven among those receiving counseling alone.

The study saw few adverse events. One participant assigned to receive nicotine-containing e-cigarettes experienced an exacerbation of chronic obstructive pulmonary disease, though it is unclear whether this was attributable to vaping.

"We desperately need information on whether e-cigarettes are effective for smoking cessation, but [we] also [need] safety data, as well," Eisenberg said. He suggested it may be wise to limit access to e-cigarettes to people who are actively attempting to quit smoking under a physician's guidance.

Researchers stopped enrollment early (after reaching 77% of target enrollment) due to a prolonged delay in the manufacturing of e-cigarettes used in the study. The study was underway before reports of vaping-linked lung injuries, and no such lung injuries occurred among study participants.

Researchers will continue to collect data for one year, with the last follow-up to be completed in September 2020. While e-cigarettes appear to be effective for smoking cessation in the short term, the one-year follow-up will show whether these effects persist over time.

###

ACC.20/WCC will take place March 28-30, bringing together cardiologists and cardiovascular specialists from around the world to share the newest discoveries in treatment and prevention. Follow @ACCinTouch, @ACCMediaCenter and #ACC20/#WCCardio for the latest news from the meeting.

The American College of Cardiology envisions a world where innovation and knowledge optimize cardiovascular care and outcomes. As the professional home for the entire cardiovascular care team, the mission of the College and its 54,000 members is to transform cardiovascular care and to improve heart health. The ACC bestows credentials upon cardiovascular professionals who meet stringent qualifications and leads in the formation of health policy, standards and guidelines. The College also provides professional medical education, disseminates cardiovascular research through its world-renowned JACC Journals, operates national registries to measure and improve care and offers cardiovascular accreditation to hospitals and institutions. For more, visit acc.org.