a significant trendp < 0.0001
Primary outcome The primary outcome of change in FMD of the brachial artery showed a significant trend in the difference among arms from TC to EC-nicotine to EC-nicotine-free (linear trend β for TC, EC-nicotine, EC-nicotine-free = 0.73%; 95% CI: 0.41 to 1.05; p < 0.0001).