Habitual electronic cigarette use was associated with a shift in cardiac autonomic balance toward sympathetic predominance and increased oxidative stress, both indicators of CV risk, according to recently published findings.
“Although tobacco cigarettes are widely recognized as the most common preventable cause of [CVD] in the world, virtually nothing is known about the [CV] risks of e-cigarettes,” Holly R. Middlekauff, MD, of the David Geffen School of Medicine at the University of California, Los Angeles, and colleagues wrote. “Rather than wait decades for epidemiological data in habitual e-cigarette users to become available, we reasoned that investigations into several of the known mechanisms by which tobacco cigarettes increase [CV] risk would provide insights in the health risk of e-cigarettes.”
Habitual e-cigarette users (n = 23) and nonuser controls (n = 19) aged 21 to 45 years, with no current tobacco smoking and no known health problems or prescription medications, were studied. The participants (35% women; 35% white; mean age, 27.6 years) were measured for heart rate variability components and oxidative stress.
The high-frequency component (0.15-0.4 Hz), an indicator of vagal activity, was decreased in e-cigarette users compared with nonusers (mean, 46.5 normalized units [nu] vs. 57.8 nu, P = .04). The low-frequency component (0.04-0.15 Hz), a mixture of both vagal and sympathetic activity, was increased in the e-cigarette users vs. nonusers (mean, 52 nu vs. 39.9 nu; P = .03). The ratio of low frequency to high frequency, reflecting the cardiac sympathovagal balance, also was increased for e-cigarette users (mean, 1.37 vs. 0.85; P = .05).
E-cigarette users had increased oxidative stress as the LDL oxidizability was increased compared with nonusers (mean, 3,801 U vs. 2,413.3 U; P = .01). No significant associations were found between e-cigarette users and high-density antioxidant/anti-inflammatory capacity and paraoxonase-1 activity.
“Although data from e-cigarette users were not compared with those from smokers of combustible cigarettes, the results of Moheimani et al demonstrate that the use of e-cigarettes is not without consequence and might impose CV harm and increase CVD risk,” Aruni Bhatnagar, PhD, director of The Diabetes and Obesity Center at the University of Louisville School of Medicine, wrote in an accompanying editorial. “Nevertheless, changes in [heart rate variability] and [LDL] oxidizability are indirect indices of [CV] injury, and it remains unclear to what extent these changes represent an increase in CVD risk.”
In a press release, Joep Perk, MD, cardiovascular prevention spokesman for the European Society of Cardiology, said: “E-cigarettes are one of the tools we have in nicotine replacement therapy, but as clinicians we should be cautious of putting people on large amounts of central nervous system stimulant drugs. Other smoking cessation schemes, such as chewing gum or patches, always include the decision to taper off use and eventually stop. This is not, in general, the case with e-cigarettes, which tend to be seen as a replacement and not a weaning off nicotine addiction. ... This is an area where we need more knowledge. The more data we collect, the more it seems that nicotine replacement strategies that taper off and ultimately end nicotine use are the way to go.” – by Cassie Homer
Disclosure: The researchers, Bhatnagar and Perk report no relevant financial disclosures.