Cardiac PET Myocardial Blood Flow Quantification Assessment of Early Cardiac Allograft Vasculopathy.

Background: Positron emission tomography (PET) has demonstrated utility for diagnostic and prognostic assessment of cardiac allograft vasculopathy (CAV) but has not been evaluated in the first year after transplant.
Objectives: The authors sought to evaluate CAV at 1 year by PET myocardial blood flow (MBF) quantification.
Methods: Adults at 2 institutions enrolled between January 2018 and March 2021 underwent prospective 3-month (baseline) and 12-month (follow-up) post-transplant PET, endomyocardial biopsy, and intravascular ultrasound examination. Epicardial CAV was assessed by intravascular ultrasound percent intimal volume (PIV) and microvascular CAV by endomyocardial biopsy.
Results: A total of 136 PET studies from 74 patients were analyzed. At 12 months, median PIV increased 5.6% (95% CI: 3.6%-7.1%) with no change in microvascular CAV incidence (baseline: 31% vs follow-up: 38%; P = 0.406) and persistent microvascular disease in 13% of patients. Median capillary density increased 30 capillaries/mm ² (95% CI: -6 to 79 capillaries/mm ² ). PET myocardial flow reserve (2.5 ± 0.7 vs 2.9 ± 0.8; P = 0.001) and stress MBF (2.7 ± 0.6 vs 2.9 ± 0.6; P = 0.008) increased, and coronary vascular resistance (CVR) (49 ± 13 vs 47 ± 11; P = 0.214) was unchanged. At 12 months, PET and PIV had modest correlation (stress MBF: r = -0.35; CVR: r = 0.33), with lower stress MBF and higher CVR across increasing PIV tertiles (all P < 0.05). Receiver-operating characteristic curves for CAV defined by upper-tertile PIV showed areas under the curve of 0.74 for stress MBF and 0.73 for CVR.
Conclusions: The 1-year post-transplant PET MBF is associated with epicardial CAV, supporting potential use for early noninvasive CAV assessment. (Early Post Transplant Cardiac Allograft Vasculopahty [ECAV]; NCT03217786).
Competing Interests: Funding Support and Author Disclosures This study was funded by a Heart and Stroke Foundation of Canada Grant in Aid (G-17-00018310) and University of Ottawa Heart Institute ORACLE Innovation Cluster Team Grant. Dr Chih is supported by a Tier 2 University of Ottawa Clinical Research Chair in Cardiac Transplantation. Dr Chong has received honoraria from Abbott and is an Abbott Advisory Board member for optical coherence tomography. Dr deKemp has received royalties from rubidium-82 PET technologies licensed to Jubilant Radiopharma and to INVIA Medical Solutions and has also received research funding and honoraria from Jubilant-DraxImage Radiopharma and IONETIX. Dr Beanlands is a University of Ottawa Distinguished Research Chair in Cardiovascular Imaging; and is a consultant for and has received research grant funding from Jubilant-DraxImage, Lantheus Medical Imaging, and General Electric Health Care. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
(Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)