Alterations in Vascular Function Associated With the Use of Combustible and Electronic Cigarettes

Abstract

Background Electronic cigarettes (e-cigarettes) have been proposed as a potential harm reduction tool for combustible cigarette smokers. The majority of adult e-cigarette users continue to smoke combustible cigarettes and are considered dual users. The vascular impact of e-cigarettes remains incompletely defined. Methods and Results We examined the association of e-cigarette use with measures of vascular function and tonometry, preclinical measures of cardiovascular injury. As part of the CITU (Cardiovascular Injury due to Tobacco Use) study, we performed noninvasive vascular function testing in individuals without known cardiovascular disease or cardiovascular disease risk factors who were nonsmokers (n=94), users of combustible cigarettes (n=285), users of e-cigarettes (n=36), or dual users (n=52). In unadjusted analyses, measures of arterial stiffness including carotid-femoral pulse wave velocity, augmentation index, carotid-radial pulse wave velocity, and central blood pressures differed across the use groups. In multivariable models adjusted for age, sex, race, and study site, combustible cigarette smokers had higher augmentation index compared with nonusers (129.8±1.5 versus 118.8±2.7, P=0.003). The augmentation index was similar between combustible cigarette smokers compared with sole e-cigarette users (129.8±1.5 versus 126.2±5.9, P=1.0) and dual users (129.8±1.5 versus 134.9±4.0, P=1.0). Endothelial cells from combustible cigarette smokers and sole e-cigarette users produced less nitric oxide in response to A23187 stimulation compared with nonsmokers, suggestive of impaired endothelial nitric oxide synthase signaling. Conclusions Our findings suggest that e-cigarette use is not associated with a more favorable vascular profile. Future longitudinal studies are needed to evaluate the long-term risks of sustained e-cigarette use.

Keywords: electronic cigarettes; e‐cigarettes; smoking; vascular function.

Figure 1

Augmentation index (AIx) is associated with tobacco product use. AIx for nonsmokers, combustible cigarette users, e‐cigarette users, and dual users following adjustment for age, sex, race, and study site. Data are expressed as least square mean±standard error.

Figure 2

Tobacco product use is associated with impaired endothelial cell (EC) phenotype. A, Nitric oxide (NO) production (4,5‐diaminofluorescein diacetate [DAF‐2DA] fluorescence) in response to A23187 stimulation in ECs freshly isolated from combustible cigarette users (n=11) and e‐cigarette users (n=5) was lower compared with nontobacco product users (n=10). B, Endothelial NO synthase (eNOS) levels quantified by immunofluorescence in ECs from nontobacco product users (n=11), combustible cigarette users (n=13), and e‐cigarette users (n=12) were similar. Data are expressed as mean±standard error.