title: Combining Baseline Distal-to-Aortic Pressure Ratio and Fractional Flow Reserve in the Assessment of Coronary Stenosis Severity.
abstract: OBJECTIVE
  This study sought to understand the physiological basis of baseline distal-to-aortic pressure ratio (Pd/Pa) and fractional flow reserve (FFR) agreement and discordance, using coronary flow reserve (CFR), stenosis resistance, and microcirculatory resistance measurements, and form there, to investigate the potential value of combining Pd/Pa with FFR in the diagnostic rationale.
  
  
  BACKGROUND
  Pd/Pa is always available before FFR assessment, and emerging data supports the notion that baseline indices can determine the ischemic potential of coronary stenosis in selected subsets.
  
  
  METHODS
  A total of 467 stenosed vessels from 363 patients were investigated with pressure and flow sensors during baseline and hyperemia: 168 vessels (135 patients) with thermodilution-derived flow, and 299 vessels (228 patients) with Doppler-derived flow.
  
  
  RESULTS
  Pd/Pa correlated more strongly with CFR than FFR (ρ difference = 0.129; p for ρ comparison <0.001). Although Pd/Pa and FFR were closely correlated (ρ = 0.798; 95% confidence interval: 0.767 to 0.828), categorical discordance was observed in 19.3% of total vessels. Such discordance was associated with the patients' clinical profile and was characterized by contrastive changes in stenosis resistance, microcirculatory resistance, and the underlying CFR. Notably, all stenosis with Pd/Pa ≤0.83 (n = 74, 15.8%) progressed to FFR ≤0.80, and although no Pd/Pa cutoff was able to exclude the development of FFR ≤0.80 in the high end of values, only 15 (10.1%) vessels with Pd/Pa ≥0.96 (n = 149, 31.9%) developed FFR ≤0.80, from which none had definite ischemia, as defined by CFR ≤1.74.
  
  
  CONCLUSIONS
  Combining baseline Pd/Pa with FFR seems to provide a more comprehensive physiological examination of stenosed coronary arteries and a closer pressure-based appraisal of the flow reserve of the downstream myocardial bed.
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain; Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; AMC Heart Centre, Academic Medical Centre-University of Amsterdam, Amsterdam, the Netherlands. Electronic address: mauroep@hotmail.com.
authors.forename: Mauro
authors.initials: M
authors.lastname: Echavarría-Pinto
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain; Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; AMC Heart Centre, Academic Medical Centre-University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Tim P
authors.initials: TP
authors.lastname: van de Hoef
authors.affiliation: AMC Heart Centre, Academic Medical Centre-University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Martijn A
authors.initials: MA
authors.lastname: van Lavieren
authors.affiliation: International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London and Imperial College Healthcare National Health Service Trust, London, United Kingdom.
authors.forename: Sukhjinder
authors.initials: S
authors.lastname: Nijjer
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain; Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Ibañez
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: Stuart
authors.initials: S
authors.lastname: Pocock
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Quirós
authors.affiliation: International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London and Imperial College Healthcare National Health Service Trust, London, United Kingdom.
authors.forename: Justin
authors.initials: J
authors.lastname: Davies
authors.affiliation: Amphia Hospital, Breda, the Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Meuwissen
authors.affiliation: International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London and Imperial College Healthcare National Health Service Trust, London, United Kingdom.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Serruys
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain; Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Macaya
authors.affiliation: AMC Heart Centre, Academic Medical Centre-University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Piek
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain; Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Escaned
mesh_terms: D000368:Aged; D001011:Aorta / Q000000981:diagnostic imaging / Q000503:physiopathology*; D062186:Arterial Pressure; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization / Q000295:instrumentation; D062906:Cardiac Catheters; D017023:Coronary Angiography; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015150:Echocardiography, Doppler; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012720:Severity of Illness Index; D013815:Thermodilution; D014160:Transducers, Pressure; D014655:Vascular Resistance
keywords: coronary flow reserve; coronary stenosis; fractional flow reserve; hyperemia; vasodilation