Thrombin generation and recurrent venous thromboembolism T. Zhu, W. Ye, F. Dali Ali, L. Carcaillon, V. Remones, M. Alhenc Gelas, P. Gaussem, P.Y. Scarabin, J. Emmerich INSERM U765, University Paris Descartes, Paris
The Problem VTE is a chronic disease with remarkably high recurrent rates. Anticoagulant therapy can prevent VTE recurrence but the optimal duration is still a matter of debate. Predicting the likelihood of recurrence is the central problem in determining duration and safety of cessation of anticoagulation.
Algorithm for the assessment of the risk for recurrent VTE (Agnelli G, et al. J Thromb Thrombolysis 2008;25:37 44 )
Thrombin generation test (TGT) 400 TGT is a global function test of the haemostatic thrombotic system. Peak Height 300 Thrombin (nm) 200 AUC = ETP Preliminary studies suggested that TGT after anticoagulation withdrawal could help to predict the risk of VTE recurrence. 100 0 0 5 10 15 20 25 30 Lag Time Time to Peak Time (min) Time to Tail
Results from AUREC study: Measurement of thrombin generation identifies patients at low risk for recurrent VTE. Hron G, et al. JAMA.2006:296:372-402
Objectives To explore the relationship between thrombin generation potential and the risk for recurrence in patients after a first episode of VTE. To determine whether endogenous microparticle levels in plasma is related with thrombin generation potential in VTE patients.
Materials and methods Design: prospective, multi centre, cohort study Participants: 766 patients after a first episode of proximal DVT and/or PE were followed up for a maximum of 5 years. Patients had a previous VTE, active cancer or indications for indefinite anticoagulation were excluded from our study. End point of study: recurrent DVT or PE
Interventions All patients were treated with unfractionated heparin or LMWH followed by oral anticoagulants for 6 months. Blood samples were taken 1 month after anticoagulation withdrawal for measurement of thrombin generation and D dimer. Hereditary thrombophilia including FV Leiden mutation, FII G20210A mutation, protein C, protein S and antithrombin deficiency were also screened in our study.
Thrombin generation assay Thrombin generation was measured in platelet poor plasma with or without the addition of phospholipids using the Thrombinoscope TM Assay (Thrombinoscope BV, Maastricht, The Netherlands). Micropaticles in plasma were measured using a functional assay (Zymuphen MP activity assay, Hyphen BioMed, neuville sur Oise,France).
R e s u l t s
Proximal DVT/PE: n=957 Excluded because of: Indefinite anticoagulation: 182; IV filter or LMWH for long-term treatment: 5; Withdrawn consent: 4; Candidates recruited: n=766 Died: 22; Cancer development: 19; Incomplete information: 31; Others: 91 Entry into Cox model: n=608 Figure: Flow diagram of the study
Table 1: Baseline characteristics of patients (n=766) Age (median, range) 50 [17 90] Male gender, n (%) 326 (42.6%) Site of thrombosis, n (%) DVT alone DVT+PE PE alone 221 (28.9%) 197 (25.7%) 348 (45.4%) Categories of VTE Unprovoked VTE, n (%) 223 (29.2%) Thrombophilic conditions, n (%) FV Leiden mutation FII G21210A mutation AT deficiency* PC deficiency* PS deficiency* ACL orβ 2 GPI Ab + 70 (10.8%) 53 ( 8.1%) 6( 1.1%) 19 (4.0%) 22( 8.0%) 50 (19.7%) Duration of follow up, years (median, range) 1.85 [0.5 5.0] * AT activity< 70%; PC avtivity< 70%; PS activity< 65%
Outcome of patients VTE recurred in 74 patients (9.7%) after a mean follow up of 2.5 years with an estimated annual incidence of 3.9%. Manifestation of recurrence: DVT (n=45), PE (n=19), DVT+PE (n=10); Death in 22 Patients Cancer development in 19 patients No exact date of AVK withdrawal: 31
Table 2: Multivariate Cox Proportional Hazards Analyses of Potential Predictors of VTE Recurrence (n=608). Hazard Ratio (95%CI) P value Sex (female) 1.20 (0.75 1.89) 0.455 Type of VTE (PE vs. DVT) 1.07 (0.64 1.77) 0.808 Unprovoked VTE 2.04 (1.28 3.24) 0.003 FV Leiden mutation 1.36 (0.68 2.72) 0.393 FII G20210A mutation 0.36 (0.09 1.45) 0.149 Residual thrombus 1.21 (0.57 2.56) 0.628 D dimer >500 μg/l 2.07 (1,20 3,57) 0.009 TGT ETP* Peak* ETP mp* Peak mp* MPs concentration 0.97 (0.56 1.70) 0.70 (0.40 1.27) 1.06 (0.61 1.84) 0.96 (0.55 1.69) 1.05 (0.60 1.84) 0.924 0.241 0.838 0.898 0.858 * Comparison of last versus first tertile of the parameter distribution
Figure: Kaplan Meier method estimates of the risk of recurrent VTE according to D dimer and provoking risk factors
Table 3: comparisons of thrombin generation and microparticles concentration in recurrence group and no recurrence group (Mean and 95%CI).. Recurrence group (n=55) No recurrence group (n=434) P value* ETP (nm*min) 1682.6 (1585.9 1779.3) 1716.5 (1676.8 1756.2) 0.535 Peak (nm) 133.7 (120.5 146.9) 135.7 (130.7 140.7) 0.711 ETP mp (nm*min) 2001.7 (1913.7 2089.7) 2033.5 (1999.9 2067.2) 0.370 Peak mp (nm) 341.1 (326.0 356.2) 347.0 (341.6 352.4) 0.443 MP concentration (nm) 11.0 (8.7 13.3) 10.4 (9.8 11.0) 0.663 * p-values are calculated in a Cox proportionnal hazards model
Figure: Relationship between MP concentration and thrombin generation (without phospholid) Peak TEP 500.00 Observed Cubic 3500.00 Observed Cubic 3000.00 400.00 2500.00 300.00 2000.00 200.00 1500.00 100.00 1000.00 0.00 0.00 10.00 20.00 30.00 ConMP 40.00 50.00 60.00 500.00 0.00 10.00 20.00 30.00 ConMP 40.00 50.00 60.00 R 2 =0.371,P<0.001 R 2 =0.068,P<0.001
Figure: Relationship between MP concentration and thrombin generation (with phospholipid) Peakmp TEPmp 600.00 Observed Linear 4000.00 Observed Linear 500.00 3000.00 400.00 300.00 2000.00 200.00 1000.00 100.00 0.00 0.00 10.00 20.00 30.00 ConMP 40.00 50.00 60.00 0.00 0.00 10.00 20.00 30.00 ConMP 40.00 50.00 60.00 R 2 =0.007,P=0.054 R 2 =0.001,P=0.521
Conclusions Neither thrombin generation potential nor endogenous microparticles in plasma are associated with the recurrent risk in patients after a first episode of VTE in our study population. However, microparticles were found to be related to thrombin generation potential in the absence of additional phospholipids in VTE patients.
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