Difference in fibrinolytic capacity in young patients with venous thrombosis or ischaemic stroke

Many recent studies focus on the common pathophysiological mechanisms and risk factors for arterial and venous thrombosis. We investigated the hypothesis that fibrinolytic capacity is similar in patients with ischaemic stroke and venous thromboembolism. Retrospective study of 604 consecutive patients (age <50 years) referred to systematic thrombophilia testing at a single regional centre. The thrombophilia test included clinical variables, genetic polymorphisms, biomarkers of coagulation and a global assay of fibrinolysis that tested the patient's blood fibrinolytic capacity by application of the euglobulin fraction of plasma to a preformed clot of plasminogen-rich bovine fibrin. The patients with venous thromboembolism (n = 284) were slightly younger (32.3 vs. 33.9 years; <0.01) than those with ischaemic stroke (n = 320), had a significantly higher prevalence of obesity (28 vs. 18%; P < 0.01), higher plasminogen activator inhibitor 1 (PAI-1) activity (12.3 vs. 11.1 IU/ml; P = 0.049) and a significantly lower fibrinolytic capacity (3.4 vs. 3.9 IU/ml; P < 0.01). The lower fibrinolytic capacity in patients with venous thromboembolism was also observed in the subgroup of patients with PAI-1 activity within the normal range (n = 430, 3.7 vs. 4.1IU/ml; P < 0.01). After adjustment for age, BMI, fibrinogen concentration, PAI-1 activity and tissue plasminogen activator activity, fibrinolytic capacity still differed significantly between the two groups. Our results indicate that the capacity for fibrinolysis is lower in young patients with venous thromboembolism than ischaemic stroke, suggesting a different mechanistic role of fibrinolysis in arterial and venous thromboembolism.