Cardiovascular effects of electronic cigarettes: A systematic review and meta-analysis

Aims The electronic cigarette is marketed as a safe alternative to tobacco smoking, but electronic cigarette cardiovascular effects remain largely unknown. We systematically reviewed and meta-analysed published literature to investigate the cardiovascular effects and associated risk from electronic cigarette use. Methods and results We searched PubMed from January 2000 to November 2017 for published studies assessing the cardiovascular effects of the electronic cigarette. Evidence suggests that the electronic cigarette negatively affects endothelial function, arterial stiffness and the long-term risk for coronary events, but these findings are from single study reports and have not been confirmed in additional studies. Conflicting evidence exists on the effects of the electronic cigarette on heart rate and blood pressure, which is mainly based on non-randomized clinical studies of moderate quality. The meta-analysis of 14 studies (N + 441 participants) suggested that despite the negative acute effects of the electronic cigarette on heart rate (pooled mean difference (MD) + 2.27, 95% confidence interval (CI): 1.64 to 2.89, p < 0.001), diastolic (pooled MD + 2.01 mmHg, 95% CI: 0.62 to 3.39, p + 0.004) and systolic blood pressure (pooled MD + 2.02 mmHg, 95% CI: 0.07 to 3.97, p + 0.042), benefits may be observed in terms of blood pressure regulation when switching from tobacco smoking to chronic electronic cigarette use (systolic blood pressure pooled MD + -7.00, 95% CI: -9.63 to -4.37, p < 0.001; diastolic blood pressure pooled MD + -3.65, 95% CI: -5.71 to -1.59, p + 0.001). Conclusions The existing evidence on the cardiovascular effects of the electronic cigarette is concerning, with several unexplored issues. Unless supported by stronger evidence, the electronic cigarette should not be labelled as a cardiovascular safe product. Future studies should delineate whether electronic cigarette use is less hazardous to cardiovascular health than conventional cigarette smoking.