Clinical experience of factor XI deficiency: the role of fresh frozen plasma and factor XI concentrate.

Factor XI deficiency is a rare autosomally transmitted coagulopathy that is associated with a variable bleeding tendency. Recently there have been reports of thrombotic events following the administration of a virally inactivated factor XI concentrate (BPL) to factor XI deficient patients. We have therefore reviewed a single centre's experience of the use of factor XI concentrate over a 6-year period and compared this to our previous experience of either no treatment or treatment with fresh frozen plasma (FFP) in 103 patients. There were 156 procedures performed without haemo- static cover. The incidence of bleeding was greatest following tonsillectomy (71%) and dental extraction (Sl'h). There was a trend for bleeding complications to be associated with lower levels of factor XI but patients with all levels of factor XI suffered bleeding complica- tions. There were 38 procedures carried out under FFP cover, with only one patient suffering excessive bleeding and no serious complications. Factor XI concentrate was given to 25 patients to cover 45 episodes. There were no bleeding complications. Three patients suffered serious complications. One patient, with a previous history of cardiovascular disease, died of a myocardial infarction and a second had an ischaemic episode resulting in a %day hospital admission. These episodes both occurred on the same day as the factor XI infusion. A third patient suffered bilateral pulmonary emboli 7 weeks after a prolonged course of factor XI concentrate. These finding suggest that factor XI concentrate should be contraindicated in patients with a history of cardiovascular disease, when FFP should be used. Guide- lines for the use of factor XI concentrates should be revised, and work performed to establish the mechanism of these thrombotic events.