Author + information
- Charalambos Vlachopoulos, MD∗ (, )
- Nikolaos Ioakeimidis, MD,
- Mahmoud Abdelrasoul, MD,
- Dimitrios Terentes-Printzios, MD,
- Christos Georgakopoulos, MD,
- Panagiota Pietri, MD,
- Christodoulos Stefanadis, MD and
- Dimitris Tousoulis, MD
- ↵∗1st Cardiology Department, Athens Medical School, Hippokration Hospital, Profiti Elia 24, Athens 14575, Greece
Smoking increases aortic stiffness and blood pressure (BP) (1), which are both important predictors of cardiovascular risk and all-cause mortality (2,3). Electronic cigarettes (EC) simulate tobacco cigarettes (TC) and have been advocated as a less harmful alternative (4). The effect of EC on aortic stiffness has not been defined. We investigated the acute effects of EC smoking on aortic stiffness and BP and compared them with the effects of TC smoking.
We studied 24 smokers (age: 30 ± 8 years) otherwise free of cardiovascular risk factors on 4 separate occasions (total 96 sessions): 1) TC over 5 min; 2) EC over 5 min; 3) EC for a period of 30 min; and 4) nothing (sham procedure) for 60 min. EC5min was chosen as a direct comparison with TC (nicotine delivery rate from EC is far lower and slower than with TC), and EC30min to mimic the common pattern of EC smoking (nicotine delivered obtained plasma levels comparable with those after 5 min of TC smoking) (5). Carotid-femoral pulse-wave velocity (PWV) was used to assess aortic stiffness. Our Institutional Research Ethics Committee approved the study protocol, and all subjects provided written informed consent. The results at various time points were compared with the baseline measurements within each arm, and between the 4 arms using paired and unpaired t-tests, respectively. The composite effect of TC or EC versus sham over time was investigated with an analysis of variance for repeated measures. Regarding PWV, the composite effect of smoking sessions versus sham over time was investigated by using mean BP as covariate.
There were no differences in all baseline measurements between the sessions. Heart rate increased in both the TC and EC 30-min sessions (by 4.0 beats/min after 5 min, p < 0.05, and by 3.1 beats/min after 30 min, respectively), whereas the effect of EC5min smoking on heart rate was minimal (p = 0.57). Both TC and EC increased systolic BP (Figure 1A) and the differences in changes of BP responses between the 2 smoking forms were not significant. Diastolic BP exhibited similar patterns of changes.
PWV increased immediately (by 0.44 m/s) after the end of TC smoking and remained increased throughout the whole period (Figure 1B). EC5min smoking induced a significant PWV increase after 15 min (by 0.19 m/s). EC30 min smoking provoked a more potent and prolonged PWV increase (peak immediately after the end of smoking, by 0.36 m/s).
Compared with TC, EC5min smoking resulted in a less potent PWV increase throughout the study (F = 4.425, p = 0.005). On the other hand, EC30min resulted in a PWV increase similar to that of TC smoking throughout the study period (F = 0.268, p = 0.615). EC30min smoking resulted in a more potent effect on PWV compared with EC5min smoking (F = 3.167, p = 0.030).
To the best of our knowledge, this is the first study dealing with various patterns of EC smoking on aortic stiffness and BP demonstrating that it clearly exerts an unfavorable effect. EC over 30 min induces an unfavorable effect on aortic stiffness similar to TC smoking. The influence of EC smoking over 5 min on aortic stiffness is not as prompt (peak effect at 15 min) and is less potent compared with the effect of TC smoking.
Given the prognostic role of aortic stiffness and increased BP for future cardiovascular events and mortality, as well as the prolonged exposure to EC smoking throughout the day matched with the strong tendency of this form of smoking to spread worldwide, especially within younger ages, our findings have important implications that could aid recommendations regarding the use of EC smoking.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
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