Low-flow mediated constriction incorporated indices as indicators of cardiovascular risk in smokers.

Background And Aims: Low-flow-mediated constriction (L-FMC), the endothelial response to reduced blood flow by forearm compression, is present in some smokers. The differences between smokers with and without L-FMC are unclear. It is also unknown whether flow-mediated total dilation (FMTD) or modified flow-mediated dilation (mFMD), both of which incorporate information concerning L-FMC, could be used to estimate cardiovascular risk. We sought to clarify the clinical factors associated with the presence of L-FMC in smokers according to sex and examine whether L-FMC incorporated indices would be better than a conventional index to estimate cardiovascular risk in smokers.

Methods: In total, 140 consecutive smokers (58 ± 13 years old) with no coronary heart disease and 48 non-smokers, who comprised the age- and sex-matched control group, were enrolled.

Results: L-FMC was demonstrated in 33.6% (47/140) and 25% (12/48) of the smokers and non-smokers, respectively. In male smokers, the predictors of the presence of L-FMC were age (p = 0.014), body mass index (BMI) (p = 0.045), and baseline brachial arterial diameter (Dbase) (p = 0.048). In female smokers, there were no predictors of the presence of L-FMC. The correlations between the Framingham risk score (FRS) and %FMTD (r = -0.34) and between FRS and %mFMD (r = -0.33) were stronger than that between FRS and conventional flow-mediated dilation (%cFMD) (r = -0.20).

Conclusions: Independent predictors of the presence of L-FMC were age, BMI, and Dbase in male smokers. L-FMC incorporated indices may be good alternatives to cFMD to estimate cardiovascular risk.