SIGNIFICANCE OF PLASMA-FIBRINOGEN IN CORONARY ARTERIAL-DISEASE - MARKER OR CAUSATIVE RISK FACTOR FOR ARTERIAL THROMBOSIS

The relationship between fibrinogen and severity of disease was measur ed in patients with coronary arterial disease (n = 301) prior to surgi cal coronary revascularisation. Platelet reactivity (shear-induced hae mostasis) was measured from non-anticoagulated blood, in vitro. Coagul ation was assessed by the clotting time of flowing native blood (dynam ic) and by the conventional (stagnant) tube tests. Significantly enhan ced platelet reactivity to shear-stress was observed when patients wit h one-vessel disease were compared to those with two- or three vessel disease (P = 0.003). Neither coagulation nor fibrinogen were significa ntly related to the severity of disease. Furthermore, patients who had myocardial infarction (n = 144) showed enhanced platelet reactivity ( P = 0.02) as compared to those who had not (n = 157). Again, neither c oagulation nor fibrinogen discriminated between these groups of patien ts. Relationship between plasma fibrinogen and platelet reactivity was also investigated in vitro. Identical blood samples with normal (220- 280 mg/dl) and elevated plasma fibrinogen (almost-equal-to 500 mg/dl) were compared by measuring platelet reactivity and coagulation from na tive blood and platelet aggregation in whole blood. The in vitro studi es suggested that plasma fibrinogen and platelet reactivity are invers ely associated. Furthermore, increased fibrinogen prolonged dynamic co agulation. These findings do not support the assertion that elevated p lasma fibrinogen is a true causative factor for coronary arterial dise ase and arterial thrombosis.