Diagnosis of Restrictive Allograft Syndrome (RAS) in Single-Lung Transplantation Using PFTs and CT-Scan Volumetry and Score

Abstract

Purpose Restrictive allograft syndrome (RAS) has been identified as a chronic lung allograft dysfunction (CLAD) with the worst prognosis after lung transplantation (LTx). Diagnostic criteria of RAS have been proposed in double-LTx (DLTx), but how to apply these criteria in single (S)-LTx remain debatable. Hence, there is a need to validate and refine these criteria in SLTx. Our aim was to investigate functional, allosensitization, and CT-scan abnormalities patterns in SLTx recipients with RAS, as compared to single LTx with BOS or in stable condition. Methods We retrospectively reviewed data from all SLTx recipients during the 2009-2015 period at Bichat hospital. Among them, RAS phenotype in SLTx was identified using criteria defined in BLTx, including both PFTs (FVC ≤ 80% of baseline or FEV1 ≤ 80% of baseline with FEV1/FVC > 0.7) and CT-scan with persistent opacities suggestive of RAS. These SLTx with RAS were compared with SLTx with BOS and stable patients. We compared outcome of PFTs (FVC, FEV1, FEV1/FVC), repeated CT-scan (both CT-volumetry and CT parenchymal score), and DSA between the 3 groups at the following 4 time points with available CT-scan: (1) at the date of best post-Tx functional status, (2) at the date of CLAD onset, defined at first irreversible decline of PFTs or graft CT-volume, or first onset of pleuroparenchymal abnormalities reflected by RAS parenchymal score; (3) at last available CT-scan; (4) at an average time between 2 and 3. Results 17 SLTx were identified with RAS diagnosis, and compared to 17 SLTx with BOS and 17 stable SLTx. In RAS patients, outcome of FVC, FEV1, CT-volume, and CT-score showed all a significant decrease from time-point of CT baseline to last CT-scan (p Conclusion RAS diagnosis remains challenging in SLTx. We observed that the increase of a CT score ≥3 may lead to earlier identification of RAS patients in this population, as compared to standard criteria of RAS initially defined in DLTx.