Thrombophilia (Hypercoagulable States) Abdulkareem Almomen, MD Professor of Medicine & Hematology, King Saud University MED 341, Feb.2014

Risk factors for thrombosis Acquired thrombophilia Hereditary thrombophilia Atherosclerosis Thrombosis Surgery trauma Immobility Estrogens Inflammation Malignancy

High-molecular-weight kininogen Tissue factor pathway inhibitor Form endothelium and inhibit coagulation thrombin activatable fibrinolysis inhibitor: which modifies fibrin to make it more resistant to the tPA-mediated plasminogen.

Thrombomodulin-thrombin complex increase the speed of activation of protein c thus activate VIII and also Thrombomodulin-thrombin complex activate TAFI to inhibit fibrinogen and tBA thus inhibit fibrinolysis Thrombomodulin by itself activate thrombin and coagulation Protien S works as a cofactor for Protein C to inactivate factor VIII and V Tissue factor pathway inhibitor inhibit factor X and VII

Risk Factors for Venous Thrombosis Inherited Acquired Mixed/unknown

Risk Factors—Inherited Antithrombin deficiency Protein C deficiency Protein S deficiency Factor V Leiden mutation (Factor V-Arg506Gln) Prothrombin gene mutation (G A transition at position 20210) Hyperhomocysteinemia

Risk Factors—Acquired Antiphospholipid antibody syndrome Myeloproliferative Disorders Heparin-induced thrombocytopenia (HIT) Prolonged air travel Advancing age Prior Thrombosis Immobilization Major surgery Malignancy Estrogens

Risk Factors—Mixed/Unknown Hyperhomocysteinemia High levels of factor VIII (8) Acquired Protein C resistance in the absence of Factor V Leiden High levels of Factor IX, XI (9,11)

Predictors of Thrombosis and Relative Risk Thrombophilic Factor Relative Risk Antithrombin deficiency 8 – 10 Protein C deficiency 7 – 10 Protein S deficiency 8 – 10 Factor V Leiden/APC resistance 3 – 7 Prothrombin 20210 A mutation 3 Elevated Factor VIII 2 – 11 Lupus Anticoagulant 11 Anticardiolipin antibodies 1.6-3.2 Mild Hyperhomocysteinemia 2.5

Site of Thrombosis vs. Risk Factor Abnormality Arterial Venous Factor V Leiden - + Prothrombin G20210A - + Antithrombin deficiency - + Protein C deficiency - + Protein S deficiency - + Hyperhomocysteinemia + + Lupus Anticoagulant + +

Other Predictors for Recurrent VTE Venous thromboembolism Idiopathic VTE Residual DVT Elevated D-dimer levels Age Gender

Hereditary Risk Factors

Antithrombin Deficiency (previously known as Antithrombin III) Inhibits coagulation by irreversibly binding the thrombogenic proteins thrombin (IIa), IXa, Xa, XIa and XIIa Antithrombin binding reaction is amplified 1000-fold by heparin, which binds to antithrombin to prevent clot formation by avidly binding thrombin and the other serine proteases An autosomal dominant inheritance Most thrombogenic disorder! IMP.

Protein C Deficiency Protein C is a vitamin K dependent glycoprotein produced in the liver In the activation of protein C, thrombin binds to thrombomodulin, a structural protein on the endothelial cell surface This complex then converts protein C to activated protein C (APC), which degrades factors Va and VIIIa, limiting thrombin production For protein C to bind, cleave and degrade factors Va and VIIIa, protein S must be available Protein C deficiency, whether inherited or acquired, may cause thrombosis when levels drop to 50% or below Protein C deficiency also occurs with surgery, trauma, pregnancy, OCP, liver or renal failure, DIC,or warfarin

 When patients with factor 5 Leiden use estrogen pills this causes SEVERE THROMBOSIS IMP!!  Protein C levels become high due to compensatory effect. [So, both high and low levels of PC lead to thrombosis].

Protein S Deficiency Protein S is an essential cofactor in the protein C pathway Protein S exists in a free and bound state 60-70% of protein S circulates bound to C4b binding protein The remaining protein S, called free PS, is the functionally active form of protein S Inherited PS deficiency is an autosomal dominant disorder, causing thrombosis when levels drop to 50% or lower

Causes of Acquired Protein S Deficiency May be due to elevated C4bBP, decreased PS synthesis(synthesized in the endothelium), or increased PS consumption C4bBP is an acute phase reactant and may be elevated in inflammation, pregnancy, SLE, causing a drop in free PS Functional PS activity may be decreased in vitamin K deficiency, warfarin, liver disease Increased PS consumption occurs in acute thrombosis, DIC, MPD, sickle cell disease It is a vitamin K dependant protein

Factor V Leiden → Activated Protein C (APC) Resistance Activated protein C (APC) is the functional form of the naturally occurring, vitamin K dependent anticoagulant, protein C APC is an anticoagulant which inactivates factors Va and VIIIa in the presence of its cofactor, protein S Alterations of the factor V molecule at APC binding sites (such as amino acid 506 in Factor V Leiden) impair, or resist APC’s ability to degrade or inactivate factor Va

Prothrombin G20210A Mutation A G-to-A substitution in nucleotide position 20210 is responsible for Prothrombin (factor II) polymorphism The presence of one allele (heterozygosity) is associated with a 3-6 fold increased for all ages and both genders The mutation (hetrozygous)causes a 30% increase in prothrombin levels(very high). Prothrombin 20210A mutation is the 2nd most common prothrombotic mutation (antithrombin resistance )

Hyperhomocysteinemia Hyperhomocysteinemia could be inherited or acquired ( deficiency of Vitamin B12, B6 and B8, IBD , Intrensic factor, RBCs damage , drugs, Methionine synthase deficiency , MTHFR (methyline tetra hydro folate reductase )Mutation, TB medication Implicated in both arterial and venous thrombosis. Treatment is by administering folic acid. Acquired is more common than inherited.  Rare autosomal recessive disorder Can cause CAD Tetrahydrofolate The pathophysiology of thrombosis in hyperhomocysteinemia is also unclear. Proposed mechanisms include direct endothelial injury, increased tissue factor activity, inhibition of protein C activation, increased platelet activation and aggregation, suppression of thrombomodulin expression, and impaired fibrinolysis by inhibition of tPA binding to its endothelial cell receptor.

Antiphospholipid Syndrome Anti phospholipid syndrome is the most important acquired cause of thrombotic disorders

Antiphospholipid Syndrome— Diagnosis Clinical Criteria Arterial or venous thrombosis Pregnancy morbidity ( recurrent fetal loss ) Thrombocytopenia Laboratory Criteria IgG or IgM anticardiolipin antibody-medium or high titer Lupus Anticoagulant b2 microglobulin Must establish at least one from each of these 2 criteria

Antiphospholipid Syndrome— Clinical Thrombosis—arterial or venous Pregnancy loss Thrombocytopenia CNS syndromes—stroke(the most common arterial event), chorea Cardiac valve disease Livedo Reticularis

Antiphospholipid Syndrome— The Lupus Anticoagulant (LAC) DRVVT- venom activates F. X directly; prolonged by LAC’s APTT- Usually prolonged, does not correct in 1:1 mix Prothrombin Time- seldom very prolonged The Sapporo criteria require at least one of the above laboratory tests to be positive and the patient to have at least one clinical manifestation of antiphospholipid syndrome such as vascular thrombosis or fetal mortality/morbidity in order to diagnose the antiphospholipid syndrome (also known as Hughes syndrome).[7] Positive laboratory test results should be seen on two separate occasions at least twelve weeks apart in order for diagnosis.

Role of phospholipids on Coagulation Tests

↑PTT

Antiphospholipid Syndrome— Anticardiolipin Antibodies ACAs are antibodies directed at a protein-phosholipid complex Detected in an ELISA assay using plates coated with cardiolipin and B2-glycoprotein

Antiphospholipid Syndrome— Treatment Patients with thrombosis- anticoagulation, INR 3 Anticoagulation is long-term —risk of thrombosis is 50% at 2 years after discontinuation Women with recurrent fetal loss and APS require LMW heparin and low-dose heparin during their pregnancies

Heparin-Induced Thrombocytopenia (HIT) HIT is mediated by an antibody that reacts with a heparin-platelet factor 4 complex to form antigen-antibody complexes These complexes bind to the platelet via its Fc receptors Cross-linking the receptors leads to platelet aggregation and release of platelet factor 4 (PF4) The released PF4 reacts with heparin to form heparin-PF4 complexes, which serve as additional sites for HIT antibody binding

Diagnosis of HIT Diagnosis made on clinical grounds HIT usually results in thrombosis rather than bleeding ( DVT and PE ) Diagnosis should be confirmed by either immunoassay( anti-platelet factor VI by ELISA) or functional tests (14C serotonin release assay) Treatment involves cessation of heparin, treatment with an alternative drug, e.g. argatroban( direct thrombin inhibitor ), and switching to warfarin

↑Tissue factor (Cancer)

TFPI

Clinical Implications In Treatment of Thrombophilia Routine screening of patients with VTE for an underlying thrombophilic defect “is not justified” However, the risk of subsequent thrombosis over 5 years in men with idiopathic VTE is 30% Any additional defect adds to risk and to possible need for prolongation of anticoagulation Furthermore, women with a history of VTE who wish to become pregnant will be treated differently if a defect were found

Screening Evaluation For “Strongly Thrombophilic” Patients Test for Factor V Leiden Genetic test for prothrombin gene mutation 20210A Functional assay of Antithrombin Functional assay of protein C Functional assay of protein S Clotting test (coagulation assay )for lupus anticoagulant/ELISA for cardiolipin antibodies Measurement of fasting total plasma homocysteine

Screening Laboratory Evaluation For “Weekly Thrombophilic” Patients Test for Factor V Leiden Genetic test for prothrombin gene mutation G20210A Measurement of fasting total plasma homocysteine Clotting assay for lupus anticoagulant /ELISA for cardiolipin antibodies

Management of Patients With Thrombophilia Risk Classification Management High Risk 2 or more spontaneous events Indefinite Anticoagulation 1 spontaneous life-threatening event (near-fatal pulmonary embolus, cerebral, mesenteric, portal vein thrombosis) 1 spontaneous event in association with antiphospholipid antibody syndrome, antithrombin deficiency, or more than 1 genetic defect Moderate Risk 1 event with a known provocative Vigorous prophylaxis in stimulus high-risk settings Asymptomatic

Heparin

Both are direct factor Xa inhibitor. For prevention

Diagnosis of Thrombophilia:  Usually they are diagnosed with venous thrombotic embolization  DVT and pulmonary embolism are the two most common manifestations of the same disease: VTE   Imaging: Duplex, spiral CT (Test of choice for PE diagnosis), Magnetic resonance venography, etc  Echocardiography, ventilation-perfusion (V/Q) scanning, and pulmonary angiography.  D-dimer Useful in low pre-test probability to exclude diagnosis of VTE Sensitivity and negative predictive value are high (~99%)  Laboratory tests: PT, PTT, protein C, S, AT (almost always low with acute thromboembolic episodes), homocysteine, anticardiolipin, factor V Leiden, FII mutation, (JAK2 mutation).

Treatment: 1. Anticoagulation: a. Heparin:  MOA: potentiates the action of antithrombin to inhibit clotting factors II and X.  Monitored by PTT because it prolongs it.  ADRs: bleeding, heparin-induced thrombocytopenia(HIT) this PE and DVT, osteoposrosis, alopecia.  5-Contraindications:previous HIT, active bleeding, haemophilia, TCP, HTN, recent surgery on eyes or brain.  6-Antidote for overdose: protamine sulphate b.Low-molecular weight heparin LMWH:  MOA: inhibit factor X directly.  Administered subcutaneous.  They cannot be monitored by PT or PTT (they affect neither)  Less monitoring needed  contraindicated in Stage V CKD. c. Warfarin (oral anticoagulant)  MOA: Vitamin K antagonist – leads to decrease in vitamin K-dependant clotting factors ( II, VII, IX, X) and protein C and S.  Monitored by PT because it is prolongs it.  Also monitored by INR (2-3 is therapeutic).  iv. Takes 4 or 5 days to have full effect so start heparin first.  ADR’s: TERATOGENIC (avoid in pregnancy)  Antidote for overdose: stop warfarin and give vitamin K.  Direct thrombin inhibitors (ximelagatran)  Factor Xa inhibitors (fonduparinux). 2. Thrombolysis: Tissue plasminogen activators (t-PA, u-PA, urokinase, alteplase) 3. Thrombectomy (arterial).