Abstract
BACKGROUND: Electronic cigarettes (e-cigs) are popular tobacco products that are currently advertised as a safer alternative to traditional cigarettes. Preliminary data, primarily from animal studies, suggests that e-cigs are associated with an increased cardiovascular disease (CVD) risk. Cardiorespiratory fitness is a marker of cardiovascular (CV) health and a predictor of CV mortality, which is diminished in traditional tobacco users. However, the effect of chronic e-cigs usage on cardiorespiratory fitness and associated CVD risk in otherwise healthy individuals without established CVD or CVD risk factor, is currently unknown. PURPOSE: The purpose of this study was to investigate the impact of chronic e-cig use on cardiorespiratory fitness and CVD risk in healthy young adults. METHODS: Ten chronic e-cig users (ECU, 4 males and 6 females; age: 24±3 yr; e-cigs usage 3±1.5 yr.) and ten demographical matched, never users (NU, 4 males and 6 females; age: 22.7±2 yr.) participated in this study. Cardiorespiratory fitness was measured by peak oxygen consumption (VO2peak) via a respiratory gas exchange analyzer during a cardiopulmonary exercise test. CVD risk was calculated using Framingham’s 30-year CVD risk score accounting for 8 risk factors (age, sex, systolic blood pressure, total cholesterol, high-density lipoprotein, presence of diabetes mellitus, hypertension treatment, and smoking status). RESULTS: Chronic e-cig users exhibited significantly lower VO2peak (ECU vs. NU; 30.9±4.9 vs. 37.8±6.4 ml/kg/min; p=0.015) and percent predicted (ECU vs. NU; 85.9±16 vs. 105.4±14 % predicted; p=0.001) when compared to never users. Framingham’s 30-year CVD risk score was significantly higher in ECU than in NU (7.7± 4.8, vs. 2.7±0.8 %; p=0.017). Furthermore, an inverse association was identified between VO2peak and 30-year CVD risk (r=-0.720; p= 0.030). CONCLUSIONS: For the first time, we have identified significantly reduced cardiorespiratory fitness, a marker of CV health and mortality risk, in chronic e-cig users when compared to never users. In addition, chronic e-cig users exhibit higher CVD risk scores. Results from our study imply a negative effect of chronic e-cig use on CV health in otherwise young, apparently healthy adults. Future studies are warranted to investigate the long-term effects of e-cig use on CV health. Supported in part by a Rapid Response Project NIDA/FDA (PRM).