Effect of enoxaparin on plasma fibrin clot properties and fibrin structure in patients with acute pulmonary embolism.

BACKGROUND

Low-molecular-weight heparins (LMWHs) influence the fibrin network structure in in vitro models. There have been no reports on LMWH-induced modifications of fibrin clot characteristics and their determinants in acute pulmonary embolism (PE).

AIM

We investigated how enoxaparin alters fibrin clot properties in acute PE patients.

METHODS

Clots were generated from plasma of 46 acute PE patients, aged 47-77 years treated with enoxaparin 1 mg/kg bid. Fibrin clot permeability (K) and clot lysis time (CLT), along with coagulation and fibrinolysis proteins were determined. Plasma fibrin clot nanostructure was assessed using scanning electron microscopy (SEM).

RESULTS

Both K and CLT were associated with anti-factor (F)Xa activity (r = 0.75, p < 0.0001 and r = -0.37, p = 0.011). Anti-FXa was positively associated with fibrin fiber diameter and the pore area, and inversely with fibrin fiber density on SEM images. Multiple regression analysis adjusted for age, body-mass index, and fibrinogen levels showed that anti-FXa activity, antithrombin activity, and FVIII activity determined K, while anti-FXa activity, plasminogen activator inhibitor-1 level, and presence of right ventricular dysfunction determined CLT.

CONCLUSIONS

We identified new laboratory and clinical factors contributing to prothrombotic plasma fibrin clot characteristics during enoxaparin treatment, which might help elucidate mechanisms underlying therapy failure in patients with acute PE.