DIVERGENCE BETWEEN CHANGES IN FIBRINOPEPTIDE A LEVELS AND ALTERATIONS IN SPECIFIC MARKERS OF THROMBIN AND FIBRIN PRODUCTION DURING CARDIAC CATHETERISATION
R E Peverill, R W Harper, T E Gan and J J Smolich
Centre for Heart and Chest Research, Department of Medicine, Monash University and Monash Medical Centre and Haematology Department, Monash Medical Centre, Clayton, Victoria
Plasma levels of fibrinopeptide A (FPA), which is cleaved from fibrinogen by thrombin during fibrin generation, have been measured during cardiac catheterisation in various cardiac conditions to assess the degree of thrombin activity and fibrin generation. However, as plasma levels of FPA are susceptible to in vivo and ex vivo artefactual elevation and can also be elevated by the presence of intravascular introducer sheaths, it is unclear whether the changes in FPA measured during cardiac catheterisation actually reflect alterations in intravascular thrombin and fibrin production. To address this question, FPA levels in an initial needle puncture and subsequent sheath blood samples were compared to simultaneously measured levels of prothrombin fragment (1+2 (F1+2), a sensitive and specific marker of thrombin generation, and soluble fibrin a direct marker of fibrin production. Blood samples were obtained from 16 patients undergoing insertion of venous sheaths and in 14 patients undergoing sheath insertion followed by right and left heart catheterisation with heparin administration. The median FPA level in the sheath sample was 120-130% higher than the needle puncture sample (p<0.03 for each patient group), whereas F1+2 and soluble fibrin levels were not significantly different between samples. Both sheath FPA and soluble fibrin levels decreased after heparin (p<0.001 and p<0.03, respectively), but only soluble fibrin was reduced to below the initial needle puncture level.
Conclusions: These findings suggest that insertion of an introducer sheath is not associated with increased intravascular thrombin or fibrin production and that changes in FPA levels in blood samples obtained via intravascular sheaths do not reliably reflect alterations in intravascular coagulation activity during cardiac catheterisation.
