Prothrombotic Fibrin Clot Phenotype Is Associated With Recurrent Pulmonary Embolism After Discontinuation of Anticoagulant Therapy.

Abstract

Pulmonary embolism (PE) is a life-threatening manifestation of venous thromboembolism with a high recurrence rate after anticoagulation cessation. Recently, we have reported that prothrombotic clot phenotype in venous thromboembolism patients is associated with an increased risk of recurrent deep-vein thrombosis. We tested whether abnormal clot properties are predictive of recurrent PE. We investigated 156 consecutive white patients aged 18 to 65 years after the first-ever provoked or unprovoked PE (n=89), with or without deep-vein thrombosis. Plasma fibrin clot permeability (Ks), turbidity measurements, calibrated automated thrombography, and efficiency of fibrinolysis using clot lysis time, maximum D-dimer levels, and rate of increase in D-dimer levels were evaluated at ≥3 months of anticoagulant therapy, at least 4 weeks since the anticoagulation withdrawal. The primary end point was recurrent PE during a median follow-up of 50 months. Recurrent PE was diagnosed in 23 (14.7%; 5%/yr) patients. Recurrent PE was associated with formation of denser fibrin networks reflected by lower Ks (P=0.007) and impaired fibrinolysis, as evidenced by prolonged clot lysis time (P=0.012) and reduced maximum rate of increase in D-dimer levels in the lysis assay (P=0.004). Patients with recurrent PE had higher plasma D-dimer (P<0.001) and thrombin peak (P=0.007) compared with the remainder, whereas turbidity measurements and maximum D-dimer levels did not differ in the recurrence. Multivariate model showed that independent predictors of recurrent PE were female sex, unprovoked venous thromboembolism, higher plasma D-dimer, reduced Ks, and reduced maximum rate of increase in D-dimer levels in the lysis assay (all P<0.05). Altered fibrin clot properties including formation of more compact clots displaying impaired susceptibility to lysis may predispose to recurrent PE.