title: Quantification of the Effect of Pressure Wire Drift on the Diagnostic Performance of Fractional Flow Reserve, Instantaneous Wave-Free Ratio, and Whole-Cycle Pd/Pa.
abstract: BACKGROUND
  Small drifts in intracoronary pressure measurements (±2 mm Hg) can affect stenosis categorization using pressure indices. This has not previously been assessed for fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and whole-cycle distal pressure/proximal pressure (Pd/Pa) indices.
  
  
  RESULTS
  Four hundred forty-seven stenoses were assessed with FFR, iFR, and whole-cycle Pd/Pa. Cut point values for significance were predefined as ≤0.8, <0.90, and <0.93, respectively. Pressure wire drift was simulated by offsetting the distal coronary pressure trace by ±2 mm Hg. FFR, iFR, and whole-cycle Pd/Pa indices were recalculated and stenosis misclassification quantified. Median (±median absolute deviation) values for FFR, iFR, and whole-cycle Pd/Pa were 0.81 (±0.11), 0.90 (±0.07), and 0.93 (±0.06), respectively. For the cut point of FFR, iFR, and whole-cycle Pd/Pa, 34.6% (155), 50.1% (224), and 62.2% (278) of values, respectively, lay within ±0.05 U. With ±2 mm Hg pressure wire drift, 21% (94), 25% (110), and 33% (148) of the study population were misclassified with FFR, iFR, and whole-cycle Pd/Pa, respectively. Both FFR and iFR had significantly lower misclassification than whole-cycle Pd/Pa (P<0.001). There was no statistically significant difference between the diagnostic performance of FFR and iFR (P=0.125).
  
  
  CONCLUSIONS
  In a substantial proportion of cases, small amounts of pressure wire drift are enough to cause stenoses to change classification. Whole-cycle Pd/Pa is more vulnerable to such reclassification than FFR and iFR.
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom. christopher.cook@nhs.net.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Cook
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Yousif
authors.initials: Y
authors.lastname: Ahmad
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Shun-Shin
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Sukhjinder
authors.initials: S
authors.lastname: Nijjer
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Rasha
authors.initials: R
authors.lastname: Al-Lamee
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Jamil
authors.initials: J
authors.lastname: Mayet
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Sayan
authors.initials: S
authors.lastname: Sen
authors.affiliation: From the International Centre for Circulatory Health, National Heart & Lung Institute, Imperial College NHS Trust, United Kingdom.
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
mesh_terms: D000368:Aged; D016477:Artifacts; D001794:Blood Pressure; D006328:Cardiac Catheterization / Q000009:adverse effects / Q000295:instrumentation*; D062906:Cardiac Catheters; D023921:Coronary Stenosis / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D003331:Coronary Vessels / Q000503:physiopathology*; D004867:Equipment Design; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014160:Transducers, Pressure
keywords: diagnosis; diastole; fractional flow reserve, myocardial; physiology; rest