title: Clinical validation of the resting pressure parameters in the assessment of functionally significant coronary stenosis; results of an independent, blinded comparison with fractional flow reserve.
abstract: BACKGROUND
  The role of resting pressure parameters, i.e. instantaneous wave-free ratio (iFR), and resting distal coronary pressure/aortic pressure (Pd/Pa) in assessing functionally significant stenosis remains controversial. We sought to assess the diagnostic performance of iFR and resting whole-cycle Pd/Pa in Asian patients.
  
  
  METHODS
  In this study, 238 consecutive lesions (no total occlusions) in which fractional flow reserve (FFR) was measured with both intravenous and intracoronary adenosine administration were included. Coded resting pressure data were sent to the core laboratory in which iFR was calculated in a blinded fashion.
  
  
  RESULTS
  FFR and iFR had unimodal distributions and the correlation was r = 0.77 (95% confidence interval, 0.71 to 0.82). In a receiver-operating-characteristic curve analysis, iFR had an area under the curve (AUC) of 0.9 at FFR ≤ 0.80. The best cut-off value for iFR was 0.90 with a sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of 76%, 86%, 82% and 80%, and 82%, respectively. The resting whole-cycle Pd/Pa cut-off of 0.91 demonstrated a diagnostic accuracy of 82% (AUC 0.9). However, iFR had higher discriminatory power than the resting whole-cycle Pd/Pa.
  
  
  CONCLUSIONS
  Both iFR and resting whole-cycle Pd/Pa showed good diagnostic performance to define the functionally significant stenosis in an independent Asian cohort distributed unimodally and without total occlusions. However, further validation is needed to explore the areas of disagreement between different physiologic parameters prior to adoption of resting pressure parameters into routine clinical practice.
authors.affiliation: Department of Internal Medicine and Cardiovascular Center, Seoul National University Hospital, Seoul, Republic of Korea; Cardiovascular Center, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
authors.forename: Jin Joo
authors.initials: JJ
authors.lastname: Park
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.forename: Chang-Wook
authors.initials: CW
authors.lastname: Nam
authors.forename: Joon-Hyung
authors.initials: JH
authors.lastname: Doh
authors.forename: Justin
authors.initials: J
authors.lastname: Davies
authors.forename: Javier
authors.initials: J
authors.lastname: Escaned
authors.forename: Bon-Kwon
authors.initials: BK
authors.lastname: Koo
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D015331:Cohort Studies; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012146:Rest / Q000502:physiology*; D016037:Single-Blind Method
keywords: Diagnostic performance; FFR; Resting whole-cycle Pd/Pa; iFR