Discordant changes in epicardial and microvascular coronary physiology after cardiac transplantation: Physiologic Investigation for Transplant Arteriopathy II (PITA II) study.
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.
Fearon
William F
WF
Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, California 94305-5637, USA. wfearon@stanford.edu
Hirohata
Atsushi
A
Nakamura
Mamoo
M
Luikart
Helen
H
Lee
David P
DP
Vagelos
Randall H
RH
Hunt
Sharon A
SA
Valantine
Hannah A
HA
Fitzgerald
Peter J
PJ
Yock
Paul G
PG
Yeung
Alan C
AC
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