title: In vitro assessment of mathematically-derived fractional flow reserve in coronary lesions with more than two sequential stenoses.
abstract: BACKGROUND
  Myocardial fractional flow reserve (FFR) is a reliable index in coronary intervention. A simple FFR measurement does not predict the true functional severity of an individual stenosis in multiple sequential coronary stenoses because of complex interaction between the stenoses. Application of the theoretical equations to predict the true FFR of individual stenosis is limited in a tandem lesion. Two novel equations applicable to a multiple sequential coronary stenoses are mathematically derived. One predicts the true FFR of each stenosis (equation A), and the other predicts the true FFR after releasing a given stenosis (equation B). The present study aimed to validate the two derived equations in an in vitro model of coronary circulation.
  
  
  RESULTS
  Predictive FFR was compared with true FFR in an in vitro model of three sequential stenoses using linear regression analysis. The difference between apparent FFR and true FFR was compared with the difference between predictive FFR and true FFR. The legitimacy of equation A was first assessed. A close correlation was found between predictive FFR and true FFR (r² = 0.92). The difference between predictive FFR and true FFR was significantly lower compared to the difference between apparent FFR and true FFR (0.18 ± 0.10 vs 0.05 ± 0.05; P<.001). The legitimacy of equation B was also assessed, and a close correlation was found (r² = 0.97). The difference was significantly lower when we applied equation B (0.13 ± 0.06 vs 0.04 ± 0.02; P<.001).
  
  
  CONCLUSIONS
  Equations A and B strongly predict the true value of FFR in the experimental model of coronary circulation.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. naritatu@kuhp.kyoto-u.ac.jp.
authors.forename: Naritatsu
authors.initials: N
authors.lastname: Saito
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Matsuo
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kawase
authors.forename: Shin
authors.initials: S
authors.lastname: Watanabe
authors.forename: Bingyuan
authors.initials: B
authors.lastname: Bao
authors.forename: Erika
authors.initials: E
authors.lastname: Yamamoto
authors.forename: Hiroki
authors.initials: H
authors.lastname: Watanabe
authors.forename: Kenji
authors.initials: K
authors.lastname: Nakatsuma
authors.forename: Katsumi
authors.initials: K
authors.lastname: Ueno
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kimura
mesh_terms: D023921:Coronary Stenosis / Q000503:physiopathology*; D053805:Fractional Flow Reserve, Myocardial / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D016014:Linear Models; D008954:Models, Biological; D008962:Models, Theoretical; D011237:Predictive Value of Tests; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results