Acquired factor X deficiency in light-chain (AL) amyloidosis is rare and associated with advanced disease.

INTRODUCTION: Systemic light chain (AL) amyloidosis can lead to an acquired coagulopathy secondary to acquired factor X (aFX) deficiency. However, it is not very clear who develops aFX deficiency in AL amyloidosis.

METHODS: We therefore undertook this single centre, retrospective study to better characterize AL amyloidosis-associated aFX deficiency.

RESULTS: Out of 121 AL patients who had FX testing at the time of their first evaluation at our institution, including 17 patients on warfarin at the time of testing, 10 out of 104 patients (9.6%) with systemic AL amyloidosis were found to have FX levels below 50%. Acquired FX deficiency was associated with advanced stage of AL amyloidosis and elevated cardiac biomarkers. Lower FX activity, advanced stage, and cardiac involvement by disease were associated with higher hazard of death on univariate analysis. On multivariate analysis, stage of AL amyloidosis was the only significant predictor of survival. Median survival time of patients with FX deficiency was 9.3 months compared to 118.4 months in those without.

CONCLUSIONS: We conclude that while aFX deficiency is rare in systemic AL amyloidosis, it is a marker of advanced disease.