Chapter 2: Anticoagulants Flashcards
How do you assess patients with AF?
- CHA2-DS2-Vasc scoring tool: assesses the risk of stroke in patients with AF.
- HASBLED scoring tool: estimates the risk of major bleeding for patients on anticoagulation to assess risk-benefit in AF.
What is the maximum total score that can be given in the CHA2-DS2-Vasc and HASBLED tool?
9
What does CHA2-DS2-Vasc mean and the point allocation?
C: congestive heart failure or left ventricular dysfunction= 1 point
H: HTN = 1 Point
A: Age > or equal to 75= 2 points
D: diabetes mellitus= 1 point
S: stroke/ TIA/systemic arterial embolism = 2 points
V: vascular disease (peripheral arterial disease, previous MI, aortic plaque) = 1 point
A: age 65-74 = 1 point
S: sex= male (0), female (1)
Max total score: 9
What does HASBLED mean and the point allocation?
H: HTN = 1 point
A: Abnormal liver function = 1 point
Abnormal renal function= 1 point
S: stroke = 1 point
B: History of major bleeding = 1 point
L: liable INRs: 1 point
E: elderly (age > or equal to 65) = 1 point
D: drugs or alcohol, drugs- other antiplatelet agents or NSAIDS, alcohol abuse = drugs(1) alcohol (1)
Total max score= 9
What treatment is needed if patient has CHA2-DS2-Vasc SCORE of 0, OR female scoring 1?
Anticoagulation for stroke prevention is not indicated
What treatment is needed for a male with the CHA2-DS2-Vasc score of 1?
Consider anticoagulation accounting for bleeding risk
Is treatment needed for patients (men and women) with a CHA2-DS2-VASC score of 2 or more?
Yes, initiate anticoagulants accounting for bleeding risk.
How long does it take for vitamin K antagonist (VKA) such as warfarin, acenocoumarol and phenindione anticoagulant effect to fully take effect?
48-72 hours
What conditions have the target INR of 2.5?
AF Antiphospholipid syndrome Bioprosthesis in the mitral position Calf vein thrombosis Cardiomyopathy DVT PE Cardioversion (higher targets such as 3, can be used for up to 4 weeks before the procedure) Recurrent VTE or PE when no longer on VKA
What conditions have a target INR of 3.5?
Recurrent DVT or PE in patients receiving anticoagulation and have INR above 2.
What are the contra-indications in patients taking VKA?
Patients with haemorrhagic stroke or clinically significant bleeding.
Avoid within 72 hours of major surgery.
Avoid in pregnancy and within 48 hours postpartum.
Monitoring requirements for VKA?
Baseline LFTs, FBC and clotting screen (prothrombin time and INR).
In the early days of treatment, INR Should be measured OD or on alternate days, then longer intervals and eventually up to every 12 weeks depending on response.
What advice should be given if a patient missed a dose of the VKA?
Doses should be taken everyday at the same time.
Usually advised to take at 6pm so that any changes in the warfarin dose can be implemented on the same day.
Patients have up to MIDNIGHT to take a dose.
NEVER DOUBLE DOSE.
Record any missed doses in the yellow book.
What do you do if patient has an INR of 5-8 with no bleeding?
Withhold 1 or 2 doses of warfarin and lower the maintenance dose.
Restart warfarin at a lower dose once INR is in range
What do you do if a patient has an INR > 8 with no bleeding?
Stop warfarin.
Give phytomenadione (Vit K1) orally using the IV preparation.
Repeat if vit k1 if INR is still high after 24 hours.
Restart warfarin when INR is less than 5.
What do you do if a patient has minor bleeding and INR 5-8?
Stop warfarin.
Give Vit K1 by slow IV injection.
Restart warfarin when INR < 5.
What do you do if a patient has major bleeding?
Stop warfarin.
Give vit k1 by slow IV injection and give dried prothrombin complex;
If dried prothrombin complex is unavailable, fresh frozen plasma can be given but it’s not as effective.
What do you do if a patient has an INR > 8 with minor bleeding?
Stop warfarin.
Give Vit K1 by slow IV injection;
Repeat dose if INR is still high after 24 hours.
Restart warfarin when INR < 5.
What are the MHRA/CHM safety information on warfarin?
- Calciphylaxis (rare): report to GP if patients develop painful skin rash. More common in patients with end stage renal disease.
- Direct antivirals to treat hep C: risk of interaction and change INR.
What are DOACS and list examples
Direct oral anticoagulants
Direct inhibitors of activated factor Xa: apixaban, rivaroxaban, endoxaban.
Direct thrombin inhibitor with rapid onset of action: dabigatran.
What is the additional drug action of endoxaban compared to apixaban and rivaroxaban?
It’s a direct AND reversible inhibitor of activated factor Xa, which prevents conversion of prothrombin to thrombin and prolongs clotting time, thereby reducing the risk of thrombus formation.
What are the advantages of DOACS?
Fixed dose Predictable anticoagulant effect Frequent monitoring is not needed No dietary interactions Fewer interactions with medications
What are the disadvantages of DOACS?
Short half life: rapid fall in effect if missed dose
Only dabigatran has a reversal agent: Idarucizumab (Praxbind)
What conditions are apixaban indicated for?
Stroke prevention in non-valvular AF.
Prevention of thromboembolism post total knee knee and hip replacement.
Treatment of DVT and PE
Prevention of recurrent DVT and PE
Available as 2.5mg and 5mg tablets
