Effects of smoking cessation on endothelial function as assessed by flow-mediated total dilation

Background In assessing the effects of smoking cessation on endothelial function, low-flow-mediated constriction (L-FMC) may provide complementary information to flow-mediated dilation (FMD). However, the value of flow-mediated total dilation (FMTD), an index that incorporates L-FMC into FMD, remains underreported. We aimed to evaluate the effect of smoking cessation on endothelial function, as assessed by FMD and FMTD, and clarify its associated clinical factors. Methods We enrolled 118 consecutive current smokers without previous coronary artery disease (72.9% were men; age: 59 +/- 11 years) who underwent smoking cessation treatment. The clinical variables %FMD, %L-FMC, and %FMTD were examined before and 20 weeks after treatment initiation. A multivariate linear regression model was used to investigate the effects of smoking cessation on %FMD and %FMTD and the interaction between smoking cessation and baseline clinical variables. Results After 20 weeks, 85 smokers (69.4% were men; age: 59 +/- 12 years) ceased smoking (abstainers), whereas 33 smokers (81.8% were men; age: 58 +/- 11 years) did not (continued smokers). The estimated group differences (abstainers - continued smokers) in changes in the %FMD and %FMTD were 0.77% (95% confidence interval [CI], -0.22-1.77%; p = 0.129) and 1.17% (95% CI, 0.16-2.18%; p = 0.024), respectively. Smoking cessation-associated improvement in %FMTD was greater in women than in men (5.41% [95% CI, 3.15-7.67%] versus 0.24% [95% CI, -0.81-1.28%]; p-value for interaction, < 0.001). Additionally, a greater %FMTD improvement was observed in patients who smoked fewer cigarettes per day (p-value for interaction, 0.042) and those who had a smaller resting baseline lumen diameter (D-base) (p-value for interaction, 0.023). Conclusions Smoking cessation was associated with an improvement in %FMTD. Sex, cigarettes smoked per day, and D-base significantly affected this improvement. The FMTD may help in risk stratification after smoking cessation.