Functional and computed tomographic evolution and survival of restrictive allograft syndrome after lung transplantation

Background: Restrictive allograft syndrome (RAS) has recently been defined as a novel phenotype of chronic lung allograft dysfunction (CLAD) after lung transplantation. The goal was to describe computed tomographic (CT) changes of RAS patients and to correlate this with spirometry and survival.

Methods: All 24 established RAS patients at our center were retrospectively included. CT scans from pre-CLAD, CLAD, post-CLAD and late-CLAD subjects were systematically evaluated by a blinded observer using a semi-quantitative scoring system. Changes in CT patterns were correlated with spirometry and survival.

Results: The most prominent CT features at diagnosis of CLAD as compared with pre-CLAD were appearance of central (p = 0.020) and peripheral ground glass opacities (p = 0.052), as well as septal and non-septal lines (p = 0.020). Survival after diagnosis of CLAD was only associated with the absolute value of forced vital capacity (FVC) at diagnosis (R = 0.46 and p = 0.021), and not with any CT alterations. Evolution of CT abnormalities after diagnosis of CLAD included significant increases in (traction) bronchiectasis (p < 0.0001), central (p = 0.051) and peripheral (p = 0.0002) consolidation, architectural deformation (p = 0.0002), volume loss (p = 0.0004) and hilus retraction (p = 0.0036). The absolute FVC decrease post-CLAD diagnosis correlated with CT alterations.

Conclusions: In the early stages of RAS, central and peripheral ground glass opacities are the most prominent feature on CT, whereas, in later stages, bronchiectasis, traction, central and peripheral consolidation, architectural deformation, volume loss and hilus retraction are more pronounced. CT changes, however, could not predict survival, whereas FVC at diagnosis of CLAD seems to be the best predictor of survival.