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.