Abstract 16097: Coagulation Factor X is Dispensable for Cardiac Catheter Thrombus Formation
Introduction: The OASIS-5 and OASIS-6 trials revealed an increased incidence of cardiac catheter thrombosis in patients with acute coronary syndromes who received the selective factor Xa inhibitor fondaparinux for systemic anticoagulation. This phenomenon is puzzling as in the traditional coagulation cascade model coagulation factor X (FX) is considered an indispensable component of the “final common pathway” where “extrinsic” and “intrinsic” pathways converge to final fibrin formation. The aim of the present study was to test in vitro the hypothesis that (i) FX deficient blood preparations allow sufficient catheter thrombus formation that (ii) is insusceptible to fondaparinux (fonda) but (iii) responsive to further unfractionated heparin (UFH) treatment. Material and methods Blood (50ml) from 8 healthy, aspirin-pretreated male donors was used for each condition investigated. Blood was centrifuged and plasma was replaced with FX-deficient plasma (FX-) or with fresh frozen plasma as control (FX+). After additional anticoagulant treatment (as indicated) blood was circuited via a Multipurpose guiding catheter for a maximum duration of 60 min. Thrombus generation and FX activity were quantified.
Results: In FX- preparations FX activity was markedly reduced compared to FX+ controls (22 ± 13 % vs. 134 ± 30 %; p<0.001). Catheter thrombus generation was present in FX- preparations, which was similar to FX- preparations additionally treated with fonda (Figure 1). FX- treatment with UFH significantly reduced catheter thrombus generation (Figure 1).
Conclusion: Our data suggest that FX is dispensable for catheter thrombus formation. As additional anti-thrombin interventions (UFH) are still effective in FX deficiency a mechanism bypassing FX in plasmatic coagulation has to be postulated. From a clinical aspect these findings indicate that any antithrombotic intervention designed to target FX exclusively is likely to fail in preventing cardiac catheter thrombosis.
- © 2010 by American Heart Association, Inc.