title: Noninvasive PET quantitative myocardial blood flow with regadenoson for assessing cardiac allograft vasculopathy in orthotopic heart transplantation patients.
abstract: Risk stratification and early detection of cardiac allograft vasculopathy (CAV) is essential in orthotopic heart transplantation (OHT) patients. This study assesses the changes in myocardial blood flow (MBF) noninvasively in OHT patients using quantitative cardiac PET with regadenoson.
  
  
  
  Twelve patients (Group 1) (8 males, 4 females, mean age 55 ± 7 years) with no history of post OHT myocardial ischemia were enrolled 5.4 ± 2.0 years after OHT. Fifteen patients (Group 2) (9 males, 6 females, mean age 71 ± 9 years) with intermediate pretest probability but not documented evidence for coronary artery disease (CAD) were also included to serve as control. Global and regional MBFs were assessed using dynamic13N-NH3PET at rest and during regadenoson-induced hyperemia. The coronary flow reserve (CFR) was also calculated as the ratio of hyperemic to resting MBF.
  
  
  
  Mean regadenoson-induced rate-pressure products were similar in both groups, while there was an increase in resting rate-pressure product in Group 1 patients. Both mean and median values of resting MBF were higher in Group 1 than Group 2 patients (1.33 ± 0.31 and 1.01 ± 0.21 mL/min/g for Groups 1 and 2, respectively, P < .001), while mean hyperemic MBF values were similar in both Groups (2.68 ± 0.84 and 2.64 ± 0.94 mL/min/g, P = NS) but median hyperemic MBF values were lower in Group 1 than Group 2 patients (2.0 vs. 2.60 mL/min/g, P = .018). Both mean and median CFR values demonstrated a significant reduction for Group 1 compared to Group 2 patients (2.07 ± 0.74 vs 2.63 ± 0.48, P = .025).
  
  
  
  This study suggests that the MBF in OHT patients may be abnormal at resting state with diminished CFR. This hints that the epicardial and microvascular coronary subsystem may be exacerbated after OHT leading to the gradual progression of CAV.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Suite 350, San Francisco, CA, 94143-0946, USA.
authors.forename: Miguel Hernandez
authors.initials: MH
authors.lastname: Pampaloni
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Suite 350, San Francisco, CA, 94143-0946, USA. uttam.shrestha@ucsf.edu.
authors.forename: Uttam M
authors.initials: UM
authors.lastname: Shrestha
authors.affiliation: Division of Cardiology, Department of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Sciammarella
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Suite 350, San Francisco, CA, 94143-0946, USA.
authors.forename: Youngho
authors.initials: Y
authors.lastname: Seo
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Suite 350, San Francisco, CA, 94143-0946, USA.
authors.forename: Grant T
authors.initials: GT
authors.lastname: Gullberg
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Suite 350, San Francisco, CA, 94143-0946, USA.|Division of Cardiology, Department of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Elias H
authors.initials: EH
authors.lastname: Botvinick
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003326:Coronary Circulation; D005260:Female; D016027:Heart Transplantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011687:Purines / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D014184:Transplantation, Homologous; D014652:Vascular Diseases / Q000000981:diagnostic imaging*
chemical_list: D011687:Purines; D011720:Pyrazoles; C430916:regadenoson
keywords: Dynamic PET; cardiac allograft vasculopathy; coronary flow reserve; orthotopic heart transplant; regadenoson