A Comparison of Enoxaparin and Unfractionated Heparin in Combination with Tirofiban during Percutaneous Coronary Intervention: Effects on Inhibition of Coagulation

Abstract number: P1616

Perrin¹ E, Ray¹ M, Wood¹ P, Walters² D

¹¹Department of Haematology, Queensland Health Pathology Service, Prince Charles Hospital, Brisbane, Australia ¹¹Department of Haematology, Queensland Health Pathology Service, Prince Charles Hospital, Brisbane, Australia ²²Department of Cardiology, Prince Charles Hospital, Brisbane, Australia

Sixty percutaneous coronary intervention (PCI) patients were randomly assigned to anticoagulation with enoxaparin or unfractionated heparin (UFH) in combination with tirofiban during PCI. The effects on inhibition of coagulation in the enoxaparin or UFH groups during the procedure were measured by changes 5 and 24 hours after the procedure in prothrombin fragment 1 + 2 (PF1 + 2), D-dimer, and thrombin/antithrombin complex (TAT). Changes in von Willebrand factor antigen (vWF) & collagen binding (CBA), cardiac troponin I (TnI), creatine kinase (CK) and C reactive protein (CRP) levels were also measured.

Results:  Compared to UFH, patients in the enoxaparin group had significantly lower PF1 + 2 levels 5 and 24 hours post PCI (P= 0.03 and 0.005 respectively). In addition, relative to UFH, the enoxaparin group had lower levels of D-dimer 5 hours post PCI (P= 0.03). The enoxaparin group showed no increase in D-dimer levels over 24 hours post PCI compared to the significant increases in the UFH group at 5 and 24 hours post PCI (P= 0.004 and 0.023 respectively). TAT levels were not different between the groups. Five hours post PCI, the vWF levels dropped with enoxaparin and not UFH and were significantly lower at this stage (P= 0.035). Both groups showed an increase in vWF after 24 hours (P= 0.001) and an increase at 24 hours in CBA with enoxaparin (P= 0.019) and UFH (P= 0.049). Changes in TnI, CK and CRP were similar with both groups. Assay results show greater dispersion with UFH compared to enoxaparin.

Conclusion:  Inhibition of the coagulation cascade during PCI is more effective with enoxaparin than UFH as indicated by lower PF1 + 2 and D-dimers levels. In addition, enoxaparin administration appears to lower vWF antigen immediately after PCI. This could reflect lower vWF release with enoxaparin.

Acknowledgement:  This study was partly sponsored by Aventis.