title: In vivo validation of mathematically derived fractional flow reserve for assessing haemodynamics of coronary tandem lesions.
abstract: OBJECTIVE
  Our aim was to propose a prediction model for the post-stenting fractional flow reserve (FFR'd,pred) at a position distal to the tandem lesion.
  
  
  RESULTS
  Using the FFR at a position proximal to the tandem lesion (FFRp), and the FFR gradients across proximal (ΔFFRp) and distal (ΔFFRd) stenoses, FFR'd,pred after treating either the distal or proximal lesion was predicted as FFRp-ΔFFRp/(1-1.33kΔFFRd) or FFRp-ΔFFRd/(1-1.33ΔFFRp), respectively. The flow fraction of the distal main branch (k) was estimated using the diameter ratio of side to distal main branches. For in vivo validation, 50 patients with a tandem lesion (diameter stenosis >50%) were evaluated. Compared to the conventional model that did not consider side branch flow, our predicted FFR showed closer correlation with the measured FFR (R2=0.83 vs. 0.57) and significant reduction in mean absolute errors (0.034±0.028 vs. 0.053±0.049, p<0.001). In particular, with a large side branch and low baseline FFR, decision making using the current model had greater predictive ability than with the conventional model.
  
  
  CONCLUSIONS
  By predicting which stenosis is more severe and/or whether the remaining lesion after the first treatment is functionally significant, a tandem prediction model can help to plan optimised stent implantation.
authors.affiliation: Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Jihoon
authors.initials: J
authors.lastname: Kweon
authors.forename: Young-Hak
authors.initials: YH
authors.lastname: Kim
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Yang
authors.forename: June-Goo
authors.initials: JG
authors.lastname: Lee
authors.forename: Jae-Hyung
authors.initials: JH
authors.lastname: Roh
authors.forename: Gary S
authors.initials: GS
authors.lastname: Mintz
authors.forename: Seung-Whan
authors.initials: SW
authors.lastname: Lee
authors.forename: Seong-Wook
authors.initials: SW
authors.lastname: Park
mesh_terms: D000368:Aged; D017023:Coronary Angiography / Q000379:methods; D023921:Coronary Stenosis / Q000503:physiopathology* / Q000628:therapy; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015607:Stents