title: Improvement in coronary haemodynamics after percutaneous coronary intervention: assessment using instantaneous wave-free ratio.
abstract: OBJECTIVE
  To determine whether the instantaneous wave-free ratio (iFR) can detect improvement in stenosis significance after percutaneous coronary intervention (PCI) and compare this with fractional flow reserve (FFR) and whole cycle Pd/Pa.
  
  
  METHODS
  A prospective observational study was undertaken in elective patients scheduled for PCI with FFR ≤ 0.80. Intracoronary pressures were measured at rest and during adenosine-mediated vasodilatation, before and after PCI. iFR, Pd/Pa and FFR values were calculated using the validated fully automated algorithms.
  
  
  METHODS
  Coronary catheter laboratories in two UK centres and one in the USA.
  
  
  METHODS
  120 coronary stenoses in 112 patients were assessed. The mean age was 63 ± 10 years, while 84% were male; 39% smokers; 33% with diabetes. Mean diameter stenosis was 68 ± 16% by quantitative coronary angiography.
  
  
  RESULTS
  Pre-PCI, mean FFR was 0.66 ± 0.14, mean iFR was 0.75 ± 0.21 and mean Pd/Pa 0.83 ± 0.16. PCI increased all indices significantly (FFR 0.89 ± 0.07, p<0.001; iFR 0.94 ± 0.05, p<0.001; Pd/Pa 0.96 ± 0.04, p<0.001). The change in iFR after intervention (0.20 ± 0.21) was similar to ΔFFR 0.22 ± 0.15 (p=0.25). ΔFFR and ΔiFR were significantly larger than resting ΔPd/Pa (0.13 ± 0.16, both p<0.001). Similar incremental changes occurred in patients with a higher prevalence of risk factors for microcirculatory disease such as diabetes and hypertension.
  
  
  CONCLUSIONS
  iFR and FFR detect the changes in coronary haemodynamics elicited by PCI. FFR and iFR have a significantly larger dynamic range than resting Pd/Pa. iFR might be used to objectively document improvement in coronary haemodynamics following PCI in a similar manner to FFR.
authors.affiliation: Imperial College London, , London, UK.
authors.forename: Sukhjinder S
authors.initials: SS
authors.lastname: Nijjer
authors.forename: Sayan
authors.initials: S
authors.lastname: Sen
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.forename: Rajesh
authors.initials: R
authors.lastname: Sachdeva
authors.forename: Florim
authors.initials: F
authors.lastname: Cuculi
authors.forename: Javier
authors.initials: J
authors.lastname: Escaned
authors.forename: Christopher
authors.initials: C
authors.lastname: Broyd
authors.forename: Nicolas
authors.initials: N
authors.lastname: Foin
authors.forename: Nearchos
authors.initials: N
authors.lastname: Hadjiloizou
authors.forename: Rodney A
authors.initials: RA
authors.lastname: Foale
authors.forename: Iqbal
authors.initials: I
authors.lastname: Malik
authors.forename: Ghada W
authors.initials: GW
authors.lastname: Mikhail
authors.forename: Amarjit S
authors.initials: AS
authors.lastname: Sethi
authors.forename: Mahmud
authors.initials: M
authors.lastname: Al-Bustami
authors.forename: Raffi R
authors.initials: RR
authors.lastname: Kaprielian
authors.forename: Masood A
authors.initials: MA
authors.lastname: Khan
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Baker
authors.forename: Michael F
authors.initials: MF
authors.lastname: Bellamy
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
authors.forename: Jamil
authors.initials: J
authors.lastname: Mayet
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Kharbanda
authors.forename: Carlo
authors.initials: C
authors.lastname: Di Mario
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
mesh_terms: D023921:Coronary Stenosis / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D062645:Percutaneous Coronary Intervention; D011446:Prospective Studies
keywords: CORONARY PHYSIOLOGY
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