Thrombosis management

Question 1

What is the anticoagulant effects of heparin?

Answer 1

Binds to antithrombin and catalyses the inactivation of thrombin, IIa, Xa, IXa, XIa and XIIa

BInds to HCH and inactivates IIz

Binds factor IXa which inhibits factor X activiation

Question 2

Mechanism of action of warfarin?

Answer 2

Vitamin K reductase inhibitor

–> Stops the reduction of Vitamin K –> stops carboxylation of factors II, VII, IX, X and XI

Question 3

Oral anti-Xa inhibitors?

Answer 3

Rivaroxaban and Apixaban

Question 4

Direct thrombin inhibitors?

Answer 4

Dabigatran

Question 5

Evidence for NOACs?

Answer 5

Non inferior to warfarin

NOACs have better safety profile - less major bleeding

Question 6

Highest risk of recurrence of VTE?

Answer 6

Unprovoked VTE

Question 7

Long term anticoagulation after VTE?

Answer 7

For unprovoked VTE only

Long term warfarin or NOACs

If doesn’t want warfarin or NOAC = aspirin
Aspirin decreases risk of recurrent VTE by 30%

Question 8

Thrombophilia testing after unprovoked VTE?

Answer 8

Most thrombophilias increase risk of a primary VTE but not recurrent VTEs

= Don’t test

Question 9

What about lupus anticoagulant?

Answer 9

Increases risk of venous and arterial thrombosis

Question 10

How to test for lupus anticoagulant?

Answer 10

Prolonged ApTT and DRVVT

ApTT not corrected with mixing test

Confirm test with dilute russel venom viper test - adding phospholipid will correct antibody

Also check for the presence of anti-cardiolipin antibody and Anti-beta2 GPI antibody

Question 11

What should be checked for if patient diagnosed with splanchic vein thrombosis?

Answer 11

Prevalence of JAK2

Question 12

What about IVC filters for preventing recurrence?

Answer 12

Nil mortality benefit

Increased mortality after 1 yr

Only for patients who can’t be anticoagulated safely

Question 13

How do you measure the presence of Dabigatran?

Answer 13

ApTT and Thrombin clotting time very sensitive to the presence of dabigatran

If normal ApTT and thrombin clotting time = minimal or no drug
If normal ApTT and prolonged thrmbin clotting time = low drug levels
If both prolonged = significant drug levels

Question 14

How do you measure the levels of dabigatran?

Answer 14

Haemaclot assay

Question 15

How do you measure the presence of anti-Xa drugs

Answer 15

Modified Anti-Xa assay

Need to know what drug the patient is taking

Question 16

How do you reverse Dabigatran

Answer 16

Idaracizimab
2.5gm bolus and repeated at 15 minutes
Works within 1 minute

Monoclonal antibody which has a greater binding affinity for dabigatran than thrombin –> neutralizes activity

Question 17

How to reverse rivaroxaban and apixaban?

Answer 17

Adexenate

Decoy Xa without anticoagulant activity
BInds drugs –> neutralizes activity

Question 18

Can NOACs be used for prosthetic heart valve prophylaxis?

Answer 18

NO

Question 19

Which side is a pregnant woman more likely to get a DVT?

Answer 19

Left side

Due to anatomy of the vessels

Question 20

Does screening for cancer in unprovoked VVTE improve outcomes?

Answer 20

10% of patients with unprovoked VTE have cancer at 12-24 months

SOME study = no difference in time to diagnosis, mortality from cancer or reduction in recurrent VTEs with extensive screening - targeted hx and ex and ix same outcomes

Question 21

Do males or females have a higher risk of recurrence of VTE?

Answer 21

Males