title: Myocardial flow reserve is influenced by both coronary artery stenosis severity and coronary risk factors in patients with suspected coronary artery disease.
abstract: OBJECTIVE
  Myocardial flow reserve (MFR) measurement has an important role in assessing the functional severity of coronary artery stenosis. However, a discrepancy between the anatomical severity of coronary artery stenosis and MFR is often observed. Such a discrepancy may be explained by coronary risk factors. In this study, we aimed to investigate the influence of coronary artery stenosis severity and risk factors on MFR.
  
  
  METHODS
  Seventy-four patients suspected to have coronary artery disease and seven age-matched healthy volunteers were enrolled. Myocardial blood flow (MBF) and MFR were measured using 15O-labelled water PET. Regional MFR was calculated in regions with significant coronary artery stenosis (stenotic regions) and in regions without significant stenosis (remote regions). The contributions of coronary artery stenosis severity and coronary risk factors were assessed using univariate and multivariate analyses.
  
  
  RESULTS
  In stenotic regions, MFR correlated inversely with coronary artery stenosis severity (r=-0.50, p<0.01). Univariate analysis did not show any significant difference in MFR between the patients with and the patients without each risk factor. In remote regions, however, MFR was significantly decreased in the diabetes and smoking groups (each p<0.05). By multivariate analysis, diabetes and smoking were independent predictors of MFR (each p<0.05). In the group with more than one risk factor, MFR was significantly lower (2.78+/-0.79) than in the other group (3.40+/-1.22, p<0.05).
  
  
  CONCLUSIONS
  MFR is influenced not only by coronary stenosis severity but also by coronary risk factors. In particular, the influence of risk factors should be considered in regions without severe coronary stenosis.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsukamoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Morita
authors.forename: Masanao
authors.initials: M
authors.lastname: Naya
authors.forename: Chietsugu
authors.initials: C
authors.lastname: Katoh
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inubushi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuge
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsui
authors.forename: Nagara
authors.initials: N
authors.lastname: Tamaki
mesh_terms: D001783:Blood Flow Velocity; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011877:Radionuclide Imaging; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012720:Severity of Illness Index