title: Fractional Flow Reserve Evaluation and Chronic Kidney Disease: Analysis From a Multicenter Italian Registry (the FREAK Study).
abstract: OBJECTIVE
  To establish if the presence of chronic kidney disease (CKD) influences fractional flow reserve (FFR) value in patients with intermediate coronary stenosis.
  
  
  BACKGROUND
  FFR-guided coronary revascularization reduces cardiac adverse events in patients with coronary artery disease. CKD impairs microcirculation and increases cardiovascular risk. Whether CKD presence may limit FFR accuracy is unknown.
  
  
  METHODS
  We used data from a multicenter prospective registry enrolling 1.004 patients undergoing FFR evaluation for intermediate stenosis. We assessed the relationship between clinical and angiographic variables and FFR measurement. CKD was defined as CrCl value ≤45 ml/min. FFR value was considered potentially flow-limiting, and therefore positive, if ≤0.80. The index of microcirculatory resistance (IMR) was calculated in 20 patients stratified according CrCl value (single-center substudy).
  
  
  RESULTS
  FFR measurement was positive in 395 (39%) patients. Overall, 131 (13%) patients had CKD. Patients with CrCl ≤45 ml/min showed significantly higher FFR values as compared to the others (0.84 ± 0.07 vs. 0.81 ± 0.08, p < 0.001). Positive FFR occurrence was lower in patients with CrCl ≤45 ml/min (27% vs. 41%, p < 0.01). After multivariable analysis, diabetes (HR 1.07, 95%CI 1.008-1.13, p = 0.03), left anterior descending (HR 1.35, 95%CI 1.27-1.43, p < 0.001) and CrCl ≤45 ml/min (HR 0.92, 95%CI 0.87-0.97, p = 0.005) emerged as independent predictors of FFR measurement. Accordingly, IMR values were higher in patients with CrCl ≤45 ml/min (32 U [28245] vs. 16 U [11220], p < 0.01).
  
  
  CONCLUSIONS
  FFR and IMR measurements differ between CKD patients and those with normal renal function. Flow-limiting FFR is less frequent in patients with CrCl ≤45 ml/min. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Cardiovascular Institute, Azienda Ospedaliero-Universitaria Di Ferrara, Cona, Ferrara, Italy. tblmtt@unife.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Tebaldi
authors.affiliation: Cardiovascular Institute, Azienda Ospedaliero-Universitaria Di Ferrara, Cona, Ferrara, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Biscaglia
authors.affiliation: Department of Cardiology, University Medical Hospital of Siena, Siena, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Fineschi
authors.affiliation: Department of Cardiology, Santa Maria Nuova Hospital, Reggio-Emilia, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Manari
authors.affiliation: Department of Cardiology, Ospedale Degli Infermi, Rimini.
authors.forename: Mila
authors.initials: M
authors.lastname: Menozzi
authors.affiliation: Division of Cardiology, "Santi Antonio E Biagio E Cesare Arrigo" Hospital, Alessandria, Italy.
authors.forename: Gioel Gabrio
authors.initials: GG
authors.lastname: Secco
authors.affiliation: Department of Heart and Vessels, S.G. Moscati Hospital, Avellino, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Di Lorenzo
authors.affiliation: Division of Cardiology Città Della Salute E Della Scienza, Hospital University of Turin, Turin, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: D'Ascenzo
authors.affiliation: Clinica Medica, Departement of Medical Science, University of Ferrara, Cona, Ferrara, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Fabbian
authors.affiliation: Cardiovascular Institute, Azienda Ospedaliero-Universitaria Di Ferrara, Cona, Ferrara, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Tumscitz
authors.affiliation: Cardiovascular Institute, Azienda Ospedaliero-Universitaria Di Ferrara, Cona, Ferrara, Italy.|Maria Cecilia Hospital, GVM Care & Research, E.S. Health Science Foundation, Cotignola, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ferrari
authors.affiliation: Cardiovascular Institute, Azienda Ospedaliero-Universitaria Di Ferrara, Cona, Ferrara, Italy.|Laboratorio per Le Tecnologie Delle Terapie Avanzate (LTTA) Center, Ferrara, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Campo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D006328:Cardiac Catheterization; D017023:Coronary Angiography; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D003404:Creatinine / Q000097:blood; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D005919:Glomerular Filtration Rate; D006801:Humans; D007558:Italy; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009204:Myocardial Revascularization; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012042:Registries; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications* / Q000175:diagnosis; D012720:Severity of Illness Index; D014655:Vascular Resistance
chemical_list: D015415:Biomarkers; D003404:Creatinine
keywords: coronary artery disease; microvascular function; renal failure