Hemostatic assessment of combined anticoagulant therapy using warfarin and prothrombin complex concentrates in a case of severe protein C deficiency

Patients with severe congenital protein (P)C deficiency require long-term anticoagulant management. Recombinant PC concentrates for prophylactic use are not available in Japan; prothrombin complex concentrates (PCC), containing factors (F)II, VII, IX, X, and PC (PPSB-HT^®), have been used ‘off-label’ in a few patients. We investigated the combined use of prophylactic PCC and Warfarin (VKA; PT-INR 2.0–2.5) in a severely PC-deficient patient in whom VKA alone did not prevent recurrent purpura. Plasma VKA-dependent factor levels and global PC function (Thrombopath^®) were assessed. Plasma activity levels of FII/FVII/FIX/FX post-infusion of PCC (6.3 unit/kg) increased 35/27/27/35 (initial level) to 59/60/38/83 IU/dl, respectively. FVII:C and FIX:C rapidly returned to baseline levels 12–24 h post-infusion, but FII:C and FX:C returned more slowly. PC antigen (< 5%) increased to ~ 15%, followed by return to baseline levels 24 h post-infusion. Global PC function was very low (%PiCi 24%), but improved post-PCC infusion. This potential was slightly detectable even at an undetectable PC level. At day 3, high levels of d-dimer and FDP were observed without thrombotic event, but these improved post-infusion. Although PCC restored VKA-dependent coagulation factors, PC contained in PCC significantly improved global anticoagulation, and was clinically beneficial in this severely deficient patient.