Findings from a cross-sectional study of electronic cigarette (e-cigarette) users showed that habitual use was associated with physiologic effects that are associated with increased cardiovascular risk.

With the rising popularity of e-cigarettes, not much is known about the possibility of associated cardiovascular risk. Researchers from the University of California, Los Angeles, CA, conducted a cross-sectional case-control study (n=42) to test whether an imbalance of cardiac autonomic tone and increased systemic oxidative stress and inflammation were detectable in otherwise healthy adults who habitually used e-cigarettes.  

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Study participants meeting the criteria were aged 21-45 years, were not current tobacco smokers, had no known health problems, and were not taking prescription medications. Healthy adult volunteers who were not e-cigarette users were enrolled as controls (n=19).

Researchers analyzed heart rate variability components for high-frequency component (0.15-0.4Hz), the low-frequency component (0.04-0.15Hz), and the ratio of low-to-high frequency. Also, the three parameters of oxidative stress were measured in plasma: low-density lipoprotein oxidizability, high-density lipoprotein antioxidant/anti-inflammatory capacity, and paraoxonase-1 activity.

Data showed the high-frequency component was significantly reduced in the e-cigarette users vs. non-users (mean 46.5 nu vs. 57.8 nu ;P=0.04). The low-frequency component (mean 52 nu vs. 39.9 nu; P=0.03) and the low-to-high frequency ratio (mean 1.37 vs. 0.85; P=0.05) were significantly higher in the e-cigarette users vs. non-users, which was consistent with sympathetic predominance.

Low-density lipoprotein oxidizability was significantly higher in e-cigarette users vs. non-users (mean 3801.0U vs. 2413.3U; P=0.01) but no significant differences were seen in high-density antioxidant/anti-inflammatory capacity and paraoxonase-1 activity.

Overall, researchers concluded that habitual e-cigarette “was associated with a shift in cardiac autonomic balance toward sympathetic predominance and increased oxidative stress, both associated with increased cardiovascular risk.” 

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