John F Eidt MD University of Arkansas for Medical Sciences Thrombophilia John F Eidt MD University of Arkansas for Medical Sciences

Thrombophilia Acquired or inherited tendency toward accelerated thrombosis

THROMBOPHILIAC? Hemophilia is to Hemophiliac as Thrombophilia is to ………? THROMBOPHILIAC?

Classification of thrombophilia 1. Qualitative/quantitative defect of coagulation factor inhibitors a) Antithrombin deficiency b) Protein C deficiency c) Protein S deficiency d) Heparin cofactor II deficiency e) Tissue factor pathway inhibitor deficiency f) Thrombomodulin deficiency 2. Increased levels/function of coagulation factors a) Activated protein C resistance and factor V Leiden b) Prothrombin gene mutation (G20210A) c) Dysfibrinogenemia and hyperfibrinogenemia d) Elevated levels of clotting factors VII, VIII, IX, XI, and XII 3. Hyperhomocysteinemia 4. Defects of the fibrinolytic system a) Plasminogen b) Tissue plasminogen activator c) Thrombin-activatable fibrinolysis inhibitor d) Factor XIII e) Lipoprotein (a) 5. Altered platelet function a) Platelet glycoprotein GPIb-IX b) GPIa-IIa c) GPIIb-IIIa

Prevalence of thrombophilia

Relative risk of first episode DVT APLA 20 Antithrombin deficiency 20 Protein C deficiency (Hetero) 10 Protein S deficiency 10 Homozygous Factor V Leiden 80 Heterozygous Factor V Leiden 7 Elevated FVIII 5 Prothrombin gene mutation 20210 3 Homocystenemia 3 OBCP 4 OBCP and heterozygous Factor V 35

? XII XIIa

XII XIIa XI XIa

XII XIIa XI XIa IX IXa

XII XIIa TENASE Complex XI XIa IX IXa Ca++ VIIIa PL VIII X Xa

XII XIIa XI XIa Tissue Factor VIIa VII IX IXa X Xa

XII XIIa XI XIa IX IXa X Xa

PROTHROMBINASE Complex XII XIIa XI XIa PROTHROMBINASE Complex IX IXa X Xa Ca++ Va PL Va II IIa (Thrombin)

Thrombin is the central bioregulatory enzyme in hemostasis XII XIIa XI XIa Thrombin is the central bioregulatory enzyme in hemostasis IX IXa X Xa Ca++ Va PL Va II IIa (Thrombin)

Pro-thrombotic actions of THROMBIN vWF(ADAMST13) XII XIIa Platelets PARS 1 &4 XI XIa IX IXa X Xa VIIIa II IIa (Thrombin) Va I Ia (Fibrin) XIIIa XIII TAFI Cross-linked Ia (Fibrin) Pro-thrombotic actions of THROMBIN

XII XIIa XI XIa Tissue Factor VIIa VII IX IXa X Xa VIII VIIIa II IIa (Thrombin) V Va I Ia (Fibrin) XIIIa XIII Cross-linked Ia (Fibrin)

Anti-thrombotic actions of ECs Binding of thrombin to thrombomodulin Activation of protein C Release of tPA Prostacyclin

Activated Protein C Thrombin Protein C TM ECPR

(PS and FV are cofactors for aPC) XII XIIa XI XIa Tissue Factor VIIa VII IX IXa aPC Vac X Xa aPC VIII VIIIa aPC II IIa (Thrombin) V Va I Ia (Fibrin) (PS and FV are cofactors for aPC)

aPC XII XIIa XI XIa Tissue Factor VIIa VII IX IXa X Xa aPC VIII VIIIa IIa (Thrombin) V Va I Ia (Fibrin) Plasmin Plasminogen tPA EC PAR1

XII XIIa Tissue Factor XI XIa VIIa VII IX IXa aPC X Xa VIII VIIIa II IIa (Thrombin) V LEIDEN Va I Ia (Fibrin) FV Leiden is NOT deactivated by APC and does not act as cofactor (FVac) for FVIIIa inactivation

XII XIIa Tissue Factor TFPI XI XIa VIIa VII IX IXa VIIa Inhibitor X Xa VIII VIIIa II IIa (Thrombin) V Va I Ia (Fibrin)

Antithrombin XII XIIa Tissue Factor XI XIa VIIa VII IX IXa X Xa VIII VIIIa II IIa (Thrombin) V Va I Ia (Fibrin)

XII XIIa Tissue Factor XI XIa VIIa VII IX IXa Heparin X Xa Antithrombin VIII VIIIa II IIa (Thrombin) V Va I Ia (Fibrin)

Antithrombin deficiency Auto dom (males=females) 1% of VTE Homozygous lethal in utero Heterozygous 40-70% of normal AT level Clinical presentation late teens and early adulthood 20-fold relative risk May be acquired – nephrotic syndrome

Clinical detection Functional assay (HCII based) Immunogenic assay for protein components One or both assays may be deficient

Clinical subtypes Type I - Decreased functional activity and decreased levels of normal protein Type II - Decreased functional activity and normal protein level Abnormalities in thrombin binding site Abnormalities in heparin binding site (lower risk)

Protein C deficiency Auto Dom Vit K dependent (II, VII, IX, X, C & S) aPC inactivates Va and VIIIa 3-5% of pts with VTE 10 fold relative risk Both functional and immunogenic deficiencies have been described Warfarin-induced skin necrosis Homozygous neonatal purpura fulminans

Protein S Deficiency Auto Dom Co-factor for aPC inactivation of Va and VIIIa Low level direct (aPC independent) inactivation of Va and VIIIa Produced by liver (vit K dependent), ECs and megakaryocytes Free (40%) and bound (60%) to C4bBP C4bBP increased in pregnancy, OBCP, inflammation and acute thrombosis results in decreased free S Warfarin-induced skin necrosis Homozygous neonatal purpura fulminans

Heparin Cofactor II Deficiency Direct thrombin inhibitor – accelerated by heparin, glycosoaminoglycans Uncommon Low risk of thrombosis Esp in association with another thrombotic factor

TFPI Tissue Factor Pathway Inhibitor Inhibits activation of factor X by tissue factor/VIIa pathway Clinical relevance is uncertain

Thrombomodulin deficiency ARIC inverse relationship between TM levels of and risk of CHD Clinical implications unknown Recombinant TM has been developed as novel anticoagulant with no hemorrhagic risk

Prothrombin Gene g20210a 2-5% in healthy population 7-18% in VTE patients Mutation in non-transcribed portion of prothrombin gene resulting in elevated levels of prothrombin Common in association with FV Leiden May have higher risk of PE than FV Leiden 1-3 fold increased risk of first VTE

Prothrombin G20210A (carrier) effect on recurrent VTE Haematologica/the hematology journal | 2007; 92(08) | 1107

Factor V Single chain 330kda glycoprotein 25% of FV is stored in platelet alpha granules Essential co-factor for Xa activation of prothrombin Also acts as co-factor for aPC inactivation of VIIIa

Factor V Leiden Arg506gln Most common inherited thrombophilia 2-10% of healthy population 20-50% of first-time VTE Common in Caucasians, but not found in other ethnic groups such as African, Chinese or Japanese A single mutational event occurred approximately 21,000 years ago 5-10 fold increased risk of first VTE Gene assay

APC resistance Addition of aPC does not prolong routine clotting assays (aPTT) 90% - due to FV Leiden (point mutation preventing Va inactivation by APC) 10% - due to increased plasma levels of factor VIII, the presence of antiphospholipid antibodies, older age, pregnancy, and the use of estrogens

Factor V Leiden (carrier) on risk of recurrent VTE haematologica/the hematology journal | 2007; 92(08) | 1107

Factor elevations (VII, VIII, IX, XI) FVIII elevation has been associated with 6-10 fold increased risk of VTE Some believe it should be included in thrombophilia workup Elevations of FVII, IX and XI of uncertain clinical relevance

Dysfibrinogenemia Variable susceptibility to degradation by plasmin Over 250 fibrinogen mutations have been described

Hyperhomocysteinemia Produced in metabolism of methionine Associated with arterial disease and venous thrombosis Acquired due to vitamin deficiency (B6, B12 and folate) or genetic (MTHFR or CBS)

Lupus anticoagulant First detected prolongation of PT in a patient with SLE Most result in prolongation of aPTT Not an anticoagulant Not only in SLE

APLA Syndrome LA and/or APLA Arterial or venous thrombosis Thrombocytopenia Recurrent fetal loss

Sapporo Criteria

APLA and Risk of Recurrent VTE Marked elevation in the risk of recurrent thrombosis –20 fold With anti-coagulants 3 – 10% risk at 3 years Without anti-coagulants 10 -29% risk at 3 years

How do APLAs lead to thrombosis? Inhibition of prostacyclin (PGI2) Inhibition of PC activation Increase PAIs Direct platelet activation Activation of endothelial cells Increased TF expression on monocytes

Testing Lupus anticoagulant (prolonged aPTT) PL CA++ Contact factor activator (a) Antiphospholipid antibodies

Common APLA immunoassays Anticardiolipin (not physiological) Anti-prothrombin Anti-beta-2-glycoprotein I Anti-phosphatidyl-serine Anti-phosphatidyl-ethanolamine Anti-phosphatidyl-choline Anti-phosophatidyl-inositol

What is cardiolipin and why test for an antibody to it? Cardiolipin is not physiologically relevant It is a widely available laboratory reagent It is used in the test for syphilis

APLA and VTE Anticoagulation for duration of positive APLA INR 2.0 – 3.0 (contrary to previous recs) Check APLA Q 6-12 mos Discontinue anticoagulant if APLA negative x2

Asymptomatic APLA Antiplatelet agents widely recommended but no proven benefit No role for therapeutic “prophylactic” anticoagulation Prophylaxis indicated for high risk events (long distance travel, surgery, immobilzation) Role of HRT and OBCP uncertain Patient education - should be informed of presence of APLAs and symptoms of VTE

APLA and arterial thrombosis Antiplatelet agents - ASA No clear evidence of benefit Most authors do not recommend anticoagulants

High risk for thrombosis: Prolonged duration of anticoagulation Antiphospholipid syndrome More than one thrombophilic defect (e.g. FV Leiden and Prothrombin gene mutation)) Previous VTE at unusual site Strong family history of thrombosis

Treatment (1) First time VTE with transient risk factor 3 months VKA E.g. surgery, immobilization 3 months VKA

Treatment (2) First time IDIOPATHIC VTE Recommend – 6-12 months VKA Suggest – indefinite (esp PE) Reliable patient Risk factors for bleeding

Treatment (3) First time VTE and cancer Recommend – 3-6 months LMWH Then indefinite VKA CLOT - Fragmin study LEE LITE - Hull

Treatment (4) First time VTE Recommend 12 months vs indefinite APLA Combined (e.g. FV Leiden and PG20210) Single factor and STRONG Family history Recommend 12 months vs indefinite

Treatment (5) First time VTE Recommend 6-12 months ATIII deficiency PC deficiency PS deficiency FV Leiden Prothrombin gene 20210 Homocysteine Elevated FVIII Recommend 6-12 months Prevent Low dose warfarin

Treatment (6) Recurrent VTE Recommend indefinite VKA

Pregnancy and venous thromboembolism Pregnancy is a hypercoagulable state No recommendations for widespread screening No prophylaxis for prior VTE and transient risk factor Prophylaxis with LMWH for pregnancy and thrombophilia (prior VTE or strong family history) Post partum anticoagulation for all with prior VTE - 6 weeks

Screening for thrombophilia The main argument in favor of screening asymptomatic relatives of patients with thrombophilia is the possibility of giving advice for primary antithrombotic prevention during circumstances potentially leading to VTE but not usually covered with prophylaxis in normal individuals (e.g. low-risk surgery or pregnancy and pueperium)

Against screening Expensive Does not alter treatment Stigmatizes patient/anxiety May have insurance/employer ramifications

Screening SOMMA J, SUSSMAN II , RAND JH. An evaluation of thrombophilia screening in an urban tertiary care medical center: a ‘‘real world’’ experience. Am J Clin Pathol 2006 July;126(1):120e127.

Does a positive family history increase the likelihood of detecting inherited thrombophilia? N=314 pts with VTE Prevalence of thrombophilia Overall 35% Positive FH (at least 1 first deg rel) - 42% Strong FH (at least 2 first deg rel) - 46% Family history and inherited thrombophilia Journal of Thrombosis and Haemostasis 4: 2182–2187 2006

Who should be tested for inherited thrombophilia? No one

Who should be tested for inherited thrombophilia? Idiopathic first time VTE Recurrent VTE Venous thromboembolism at early age Thrombosis in an unusual site, eg mesenteric vein, cerebral vein etc Unexplained neonatal thrombosis Skin necrosis, particularly if on VKA Arterial thrombosis before the age 30 years Unexplained prolonged activated partial thromboplastin time Patients with recurrent fetal loss Relatives of patients with thrombophilic abnormality – very controversial