IN-VIVO COAGULATION ACTIVATION FOLLOWING INFUSION OF HIGHLY PURIFIED FACTOR-XI CONCENTRATE

The use of factor XI concentrates has been associated with thrombosis. Plasma markers of coagulation activation were measured before and 30, 60, 120 and 240 min after six infusions of the BPL factor XI concentr ate. Five studies were completed before surgical intervention, one was undertaken in a patient with an intracerebral haemorrhage. Significan t elevation of levels of fibrinopeptide A (FpA) (P < 0.05) and thrombi n-antithrombin (TAT) were demonstrated following six infusions and pro thrombin fragment F1.2 following four. Levels of all three markers had risen 60 min following concentrate administration and FpA levels rema ined elevated throughout the study period. Levels of D-dimer rose in f our patients at 240 min. These results indicate significant thrombin g eneration by 60 min and subsequent plasmin generation consistent with coagulation activation by the factor XI concentrate. The greatest elev ation of activation markers was seen in those subjects with pre-existi ng coagulation activation. We advise caution in the use of these produ cts and awareness of the risks in patients who may already have activa ted coagulation states.