Secondary thrombotic microangiopathy following lung transplantation: a multicenter European cohort study.

Secondary thrombotic microangiopathy (sTMA) is a rare but severe complication after lung transplantation. We performed a multicenter retrospective cohort study including adult lung transplant recipients diagnosed with de novo sTMA between 2010 and 2023 across five European transplant centers. The primary outcome was incidence of sTMA, with secondary outcomes including clinical presentation, treatment strategies, renal outcomes, and survival. Among 3,747 lung transplantations, 49 cases of sTMA were identified, corresponding to an incidence of 1.33%. Median time to diagnosis was 312 days (IQR 93-546), with 53% occurring within the first post-transplant year. All patients presented with acute kidney injury and laboratory signs of hemolysis, neurological complications were observed in 8%. Therapeutic approaches included plasma exchange (46.9%), anti-C5 therapy (24.5%), and sequential plasma exchange followed by complement inhibition (10.2%). At follow-up, 65.3% developed chronic kidney disease, 20.4% progressed to end-stage renal disease, and 10.2% died during the acute episode. No significant association between treatment modality and renal or survival outcomes was observed. sTMA after lung transplantation is infrequent but associated with substantial renal morbidity and mortality. Early recognition through assessment of hemolysis and kidney injury, supported by renal biopsy in selected cases, may facilitate timely diagnosis and management.