P5166Electronic cigarette smoking increases of arterial stifness and oxidative stress to a lesser extent than a single normal cigarette: an acute and chronic study

Abstract

Background: Electronic cigarette is proposed as a bridge to smoking cessation. In this study we examined its effects on aortic elasticity, exhaled CO concentration, and oxidative stress both acutely and after 1 month of use. Methods: Seventy current smokers (mean age 48 years±5) without cardiovascular disease participated in the study. In the acute phase the subjects were randomized to smoke either a single normal or an electronic cigarette for 7 min (simulating the duration of a normal cigarette smoking), and after a 40 minute washout period were crossed over to the alternative cigarette. Of the 70 subjects 35 used a nicotine-free electronic cigarette fluid during the acute phase protocol and the remaining 35, an electronic cigarette fluid with a nicotine concentration of 12 mg/dL. All 70 subjects smoked an electronic cigarette with nicotine concentration of the fluid of 12 mg/dL for one month. Measurements were performed at baseline and after smoking the normal or electronic cigarette as well as after 1 month of electronic cigarette smoking. In both acute and chronic phases, we measured a) the aortic PWV (PWV) and augmentation index (AIx) by Arteriograph and Complior; b) the exhaled CO level (parts per million-ppm) as a smoking status marker; and c) the plasma malondialdehyde (MDA) levels as an oxidative stress burden index. Results: In the acute phase, compared to baseline, PWV, exhaled CO, and MDA levels were lower after the electronic compared to the normal cigarette smoking (9.3±0.2 vs 10.3±0.2 vs 10.8±0.2 m/s, p<0.05; 12.9±0.7 vs. 12±0.6 vs 14.9±0.7 ppm, p<0.001; 1.09±0.1 vs 1.17±0.1 vs 1.28±0.1 μmol/L, p<0.001, respectively). In addition, nicotine-free electronic cigarette caused a significantly smaller increase of arterial stiffness, compared to the nicotine containing fluid (-PWV=+0.3 vs +0.9m/s, p<0.05, respectively). In the chronic phase we observed a significant improvement of AIx, as well as of MDA compared to baseline (25.6±2% vs 29.5±2%, p=0.01; 1.09±0.1 vs 1.22±0.1 μmol/L, p<0.05 respectively). Conclusions: Electronic cigarette smoking causes a smaller increase of arterial stiffness and oxidative stress, compared to a single normal cigarette in an acute setting. Replacement of normal cigarettes by a moderate nicotine concentration electronic cigarette results in improved aortic elasticity and oxidative stress within 1 month.