Bivalirudin, a
direct thrombin inhibitor binds specifically and reversibly to both
fibrin-bound and unbound
thrombin.
Bivalirudin is approved for use as an
anticoagulant in patients undergoing
percutaneous coronary intervention. The OASIS-5 trial presented a significant increase in
cardiac catheter thrombosis for the pentasaccharid
fondaparinux compared to
enoxaparin.
Catheter thrombosis has never been reported in any trial using
bivalirudin. Our study compared the development of
catheter thrombosis for
bivalirudin,
enoxaparin, and
unfractionated heparin in a controlled in-vitro environment. Ten healthy male volunteers were pretreated with
aspirin 500 mg 2 hours before venesection of 50 ml of blood. The seven groups of
anticoagulant combinations tested were: UFH, UFH +
eptifibatide,
enoxaparin,
enoxaparin +
eptifibatide,
bivalirudin bolus,
bivalirudin +
eptifibatide,
bivalirudin bolus + continuous infusion. The blood/
anticoagulant mix continuously circulated through a cardiac guiding
catheter for 60 minutes or until the
catheter became blocked with
thrombus.
Thrombus development was assessed by weighing each
catheter before and after the procedure. Electron microscopy was used to quantify the degree of erythrocyte, platelet and
fibrin deposition. Following anticoagulation with bolus dose
bivalirudin, the
catheter was invariably occluded with
thrombus after 33 minutes of circulation. However, a continuous infusion of
Bivalirudin prevented the development of occlusive
catheter thrombosis. In the bolus
bivalirudin group the mean
thrombus weight was significantly greater than in all other groups (p-value < 0.01 in all analyses).
Bivalirudin given as a bolus was not sufficient to prevent
cardiac catheter thrombosis in our in-vitro study. However, a continuous infusion of
bivalirudin had similar anti-thrombotic efficacy compared to other treatment strategies.