FVIIa-antithrombin levels in early and late preeclampsia

Preeclampsia (PE) is associated with a hypercoagulability state. According to the gestational age (GA) at the onset of the disease, PE has been classified as early (GA<34weeks) and late (GA≥34weeks). It has been admitted that early PE is associated with ischemic placental lesions, while in late PE an adequate or slightly impaired placentation occurs, which suggests that the two clinical forms have distinct etiology. Tissue factor (TF) binds and activates plasma factor VII triggering the coagulation. The inhibitor antithrombin (AT), along with tissue factor pathway inhibitor, acts as an inhibitor of the FVIIa-TF pathway. Once the TF-FVIIa complex is formed, the binding and transfer of FVIIa to AT is facilitated and FVIIa activity is inhibited.

We evaluated the FVIIa-AT complex levels in pregnant women with early and late severe PE (sPE), in order to verify if this biomarker can be useful for discriminating the two forms of the disease.

We evaluated 26 pregnant with severe early PE and 19 pregnant with severe late PE. FVIIa-AT levels were measured by STACLOT® (Diagnostica Stago). Statistical analysis was done by Mann-Whitney test.

Increased FVIIa-AT levels were found in early sPE [148.4pM (137.1)] compared to late sPE [95.9pM (66.5)] (P=0.046), which suggests a higher pro-coagulant state when PE onset occurs before 34weeks of gestation.

These pioneer data allow inferring the relevance of FVIIa-AT as a device for early sPE diagnosis. However, the clinical relevance of FVIIa-AT complex surely needs to be fully clarified.