title: Discordant changes in epicardial and microvascular coronary physiology after cardiac transplantation: Physiologic Investigation for Transplant Arteriopathy II (PITA II) study.
abstract: BACKGROUND
  Investigating changes in coronary physiology that occur after cardiac transplantation has been challenging. Simultaneous and independent assessment of the epicardial artery by measuring fractional flow reserve (FFR) and of the microvasculature by calculating the index of microvascular resistance (IMR) with a single coronary pressure wire may be useful.
  
  
  METHODS
  Twenty-five asymptomatic patients with normal coronary angiograms underwent FFR, thermodilution-derived IMR and coronary flow reserve (CFR) and intravascular ultrasound (IVUS) evaluation soon after cardiac transplantation and 1 year later.
  
  
  RESULTS
  FFR significantly worsened (0.90 +/- 0.05 at baseline to 0.85 +/- 0.06 at 1 year, p = 0.004). FFR correlated strongly with percent plaque volume as measured by IVUS (r = -0.58, p < 0.0001). IMR improved significantly (29.2 +/- 15.9 at baseline to 19.3 +/- 7.6 units at 1 year, p = 0.007). CFR increased, but not significantly (2.6 +/- 1.4 at baseline to 3.2 +/- 1.2 at 1 year, p = not significant). Diabetes and donor heart ischemic time independently predicted baseline IMR. Treatment with rapamycin independently predicted FFR at 1 year.
  
  
  CONCLUSIONS
  New coronary physiologic measures, FFR and IMR, show that epicardial artery physiology worsens and correlates with anatomic changes, whereas microvascular physiology improves during the first year after cardiac transplantation. CFR, the traditional method for evaluating coronary circulatory physiology, did not identify these changes.
authors.affiliation: Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, California 94305-5637, USA. wfearon@stanford.edu
authors.forename: William F
authors.initials: WF
authors.lastname: Fearon
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirohata
authors.forename: Mamoo
authors.initials: M
authors.lastname: Nakamura
authors.forename: Helen
authors.initials: H
authors.lastname: Luikart
authors.forename: David P
authors.initials: DP
authors.lastname: Lee
authors.forename: Randall H
authors.initials: RH
authors.lastname: Vagelos
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Hunt
authors.forename: Hannah A
authors.initials: HA
authors.lastname: Valantine
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Fitzgerald
authors.forename: Paul G
authors.initials: PG
authors.lastname: Yock
authors.forename: Alan C
authors.initials: AC
authors.lastname: Yeung
mesh_terms: D006328:Cardiac Catheterization; D017023:Coronary Angiography; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D016027:Heart Transplantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology*; D011184:Postoperative Period; D013815:Thermodilution / Q000379:methods; D018084:Ultrasonography, Interventional; D014655:Vascular Resistance