Intraoperative use of low-dose recombinant activated factor VII during thoracic aortic operations.

Bleeding may be a problem in patients undergoing cardiac surgery. Prohemostatic strategies, mostly antifibrinolytic agents, have been shown to be effective in reducing perioperative blood loss and transfusion requirements. These strategies were also shown to reduce the incidence of clinically relevant outcomes, such as reoperation, perioperative complications and mortality. Recombinant factor VIIa is a prohemostatic agent that can reduce perioperative blood loss. Previous studies and meta-analyses have concluded that recombinant factor VIIa can reduce perioperative blood loss and transfusion requirements but also found an increased risk of arterial thrombosis, including coronary artery events and ischemic stroke.

Andersen et al. performed an observational study of low dose (< 60 μg/kg) recombinant factor VIIa in patients undergoing thoracic aortic surgery. Seventy-seven patients receiving intraoperative factor VIIa (median dose 32 μg/kg) were matched (propensity-adjusted) with patients not receiving factor VIIa. Patients who received factor VIIa showed an improvement of routine coagulation times (aPTT and INR) and required less blood products compared to controls. There were no differences in thromboembolic complications between recombinant factor VIIa-treated patients and controls. This study adds to the evidence that recombinant factor VIIa may be effective in reducing perioperative blood loss and transfusion rates in major surgery and as such it is an interesting observation. However, due to the observational design of the study, selection bias and potential confounding in selection of controls (however propensity-adjusted the matching may have been), the value of this observation is somewhat limited. Also, the observation that factor VIIa affects coagulation parameters is not very useful, since this is likely to be an ex vivo effect as routine coagulation tests are very sensitive to even very low concentrations of factor VIIa. The study is probably too small to make meaningful statements regarding the safety of factor VIIa in this specific clinical setting.

– Marcel Levi