Relationship Among Radiological Measurements of Anterior Mediastinal Fat and Outcomes of Lung Transplantation in Fibrotic Patients.

Objective: Lung transplantation (LT) for pulmonary fibrosis is related to higher mortality than other transplant indications. We aim to assess whether the amount of anterior mediastinal fat (AMF) was associated to early and long-term outcomes in fibrotic patients undergoing LT.

Methods: Retrospective analysis of 92 consecutive single lung transplants (SLT) for pulmonary fibrosis over a 10-year period. AMF dimensions were measured on preoperative CT-scan: anteroposterior axis (AP), transverse axis (T), and height (H). AMF volumes (V) were calculated by the formula: AP×T×H×3.14/6. According to the radiological AMF dimensions, patients were distributed into two groups: low-AMF (V<20cm) and high-AMF (V>20cm), and early and long-term outcomes were compared by univariable and multivariable analyses.

Results: There were 92 SLT: 73M/19F, 53±11 [14-68] years old. 30-Day mortality (low-AMF vs. high-AMF): 5 (5.4%) vs. 15 (16.3%), p=0.014. Patients developing primary graft dysfunction within 72h post-transplant, and those dying within 30 days post-transplant presented higher AMF volumes: 21.1±19.8 vs. 43.3±24.7cm (p=0.03) and 24.4±24.2 vs. 56.9±63.6cm (p<0.01) respectively. Overall survival (low-AMF vs. high-AMF) (1, 3, and 5 years): 85%, 81%, 78% vs. 55%, 40%, 33% (p<0.001). Factors predicting 30-day mortality were: BMI (HR=0.77, p=0.011), AMF volume (HR=1.04, p=0.018), CPB (HR=1.42, p=0.002), ischaemic time (HR=1.01, p=0.009). Factors predicting survival were: AMF volume (HR=1.02, p<0.001), CPB (HR=3.17, p=0.003), ischaemic time (HR=1.01, p=0.001).

Conclusion: Preoperative radiological assessment of mediastinal fat dimensions and volumes may be a useful tool to identify fibrotic patients at higher risk of mortality after single lung transplantation.