Antithrombin antigen and activity in patients with acquired antithrombin deficiency-is there a difference?

Rivaroxaban for the treatment of venous thromboembolism in patients with nephrotic syndrome and low AT-III: A pilot study

The anticoagulation effect of heparin requires adequate serum antithrombin (AT)-III levels. Rivaroxaban, however, exhibits its anticoagulation effects independent of AT-III. The aim of the present study was to evaluate the efficacy and safety of rivaroxaban as a treatment for venous thromboembolism in patients with AT-III deficiency due to nephrotic syndrome. Patients with nephrotic syndrome and low serum concentration and functional activity of AT-III and venous thromboembolism were randomly assigned to the rivaroxaban group (n=8) and low weight molecular heparin group (n=8). The patients were treated for 4 weeks and evaluated at weeks 2 and 4. The primary endpoint was thrombus dissolution or a >90% decrease in thrombus volume in 4 weeks. Secondary endpoints included an increase in the volume of the pre-existing thrombosis and safety assessments. In each of the two groups, 7/8 patients achieved a primary endpoint. At week 2, 5 patients in the rivaroxaban group and 4 in the low weight molecular heparin group had achieved the primary endpoint. Notably, at week 2 the patients whose AT-III levels and functional activity remained low in the low weight molecular heparin group did not achieve the primary endpoint. The adverse effects were similar in both groups, with no severe hemorrhage observed. In conclusion, the results of this pilot study demonstrate that rivaroxaban may be an effective, safe, single-agent approach for treating vein thromboembolism in patients with nephrotic syndrome and low AT-III levels. The potential benefits of rivaroxaban over low weight molecular heparin treatment require further investigation with a larger sample size in order to validate the findings of the present study.