Anticoagulants Flashcards
What do you need to consider prior to giving patients anticoagulants? (1)
Benefits vs. Risk (bleeding)
When would you consider monitoring the patient if not taking anticoagulants? (2)
Review at 65 yrs.
Or if develop diabetes, HF, PAD, CHD, stroke, TIA or systemic thromboembolism.
Explain the use of antocoagulants in haemodynamically unstable AF. (1)
Heparin at initial presentation and continue until appropriate anticoagulant is started.
When would you consider offering anticoagulants in patients with confirmed AF < 48 hrs (haemodynamically stable)? (4)
- Stable sinus rhythm isn’t successfully restored within the same 48-hr period after onset.
- High risk of AF recurrence (Hx of failed cardioversion, structural heart disease, prolonged AF > 12 months) or previous recurrences.
- Based on CHAD2VASc.
When would you consider offering anticoagulation in AF? (6)
Offer if CHADsVASc = 2+
Consider in male biological sex = 1
Apixaban, Dabigatran, Edoxaban + Rivaroxaban = recommended options.
DOAC c/i, not tolerated or unsuitable in people with AF, offer Vitamin K antagonist:
- If already on warfarin, discuss option switching treatment at their next routine appointment, accounting person’s time in TTR.
Don’t offer anticoagulation to people aged < 65 yrs with AF and no risk factors other than their sex.
Don’t withhold anticoagulation solely because of age or risk of falls.
When would you consider assessing bleeding risk? (2)
Starting anticoagulants
Reviewing patients taking anticoagulants.
What does personalised AF care consist of? (4)
Stroke awareness and prevention
Rate/rhythm control + management
Who to contact for advice/psychological support.
Information on cause, effects and possible complications AF.
State the particulars for CHA2DS2VASc. (8)
CHD/LV dysfunction = 1
HPT = 1
Age >= 75 yrs = 2
Diabetes = 1
Stroke/TIA/TE = 2
Vascular disease (prior MI,PAD,Aortic plaque) = 1
Age (65-74 yrs) =1
Sex (female) = 1
Explain the use of ORBIT tool. (3)
Bleeding risk tool for AF.
Score of 2 for:
- Males with haemoglobin < 130g/L or haematocrit < 40%
- Females with haemoglobin <120g/L or haematocrit < 36%.
- People with Hx of bleeding (e.g. GI/intracranial bleeding or haemorrhagic stroke)
Score of 1 for people:
- Aged > 74 yrs.
- eGFR = < 60ml/min
- Tx with antiplatelets
(3
What are the severity ranges for ORBIT tool? (3)
0-2 - Low
3 - Medium
4-7 - High
What are the limitations of ORBIT tool? (3)
Doesn’t account choice of anticoagulation.
Not including all modifiable risk factors including HAS-BLED.
Not recommended as a bleeding risk tool for other conditions e.g. VTE.
What particulars makes up the HAS-BLED score? (8)
All with a score of 1:
- HPT (systolic >= 160mmHg)
- Abnormal renal/liver function
- Age >=65 yrs
- Past stroke
- Bleeding
- Labile INRs
- Taking other drugs
- Alcohol intake at same time.
What does a HAS-BLED score of 3 or more indicate? (1)
Increased 1 year bleed risk on anticoagulation. Risk is for IC bleed, bleed requiring hospitalisation or haemoglobin drip > 2g/L or needs transfusion.
What are the risk factors for bleeding? (5)
Uncontrolled HPT
Poor INR control in patients on vitamin K antagonists.
Medication (Antiplatelet, SSRI, NSAIDs)
Harmful alcohol consumption
Reversible causes of anaemia.
What should be discussed with the patient regarding to starting anticoagulation? (3)
Benefits vs risks.
Reduces risk of stroke
Don’t withhold solely due to patient’s risk of falls.
What factors would you need to consider to determine choice of anticoagulants? (4)
+/- of anticoagulants.
Patient factors: weight, renal function
Reversal agents
Monitoring
What are the main differences of warfarin vs. DOACs? (2)
DOACs have predictable pharmacokinetics, coagulation control doesn’t need to be monitored vs. Warfarin needs regular blood tests for INR monitoring.
Major bleeds
What is the reversal agent for Warfarin? (1)
Phytomenadione (Vitamin K)
What is the reversal agent for Dabigatran? (1)
Idarucizumab (available but expensive)
What is the reversal agent for Apixaban and Rivaroxaban? (1)
Andexanet Alfa (available but expensive)
What is the reversal agent for Edoxaban? (1)
No specific reversal agent.
What does MHRA state about the use of DOACs? (4)
High risk of recurrent thrombotic events in patients with anti phospholipid syndrome.
Bleeding risk and reversal agents.
Dose adjustments in people with renal impairment.
Rivaroxaban (Xarelto) = 15mg and 20mg tablets taken with food.
What are the main features of Apixaban? (5)
Direct inhibitor of activated factor X (factor Xa).
Reversal agents = andexanet alfa
BD daily.
When used for stroke prophylaxis and systemic embolism in non-valvular AF, reduce dose to 2.5mg BD if:
- Serum creatinine 133mcmol/L and over AND is associated with one of the following:
- 80 yrs and over OR
- Body weight <=60kg
- Creatinine clearance 15-29ml/minute.
What are the main features of Rivaroxaban? (6)
Direct inhibit of activated factor X (factor Xa)
Reversal agent = Andaxanet Alfa
15-20mg licensed for stroke prophylaxis in AF (taken with food.)
Renal impairment:
- Reduce dose to 15mg CrCl 15-49ml/min
- Caution if CrCl 15-29ml/min, avoid if CrCl < 15ml/min.
New licensing:
- DVT prophylaxis following total knee replacement and hip replacement. (10mg OD dose)
- Atherothrombotic event prevention following an ACS with elevated cardiac bio markers (low dose Rivaroxaban 2.5mg + aspirin alone or aspirin + clopidogrel)
What are the main features of Edoxaban? (5)
Direct and reversible inhibitor factor Xa
No specific reversal agents.
Stroke prophylaxis and systemic embolism in non-valvular AF in patients with at least 1 risk factor from CHADSVASc.
Weight <61kg -> 30mg.
Renal function:
- Avoid if CrCl = < 15ml/min
- 30mg OD if CrCl = 15-50ml/min.
What are the main features of Dabigatran? (7)
Direct thrombin inhibitor
C/i:
- CrCl < 30ml/min
- Current/recent GI ulcer
- Elevated ALT/AST (x2 ULN)
S/e
Interactions
Renal function
Reversal agents = Idarucizumab.
When to use warfarin? (8)
Mechanical heart valve
Moderate to severe mitral stenosis
Antiphospholipid antibodies
Pregnancy
Breastfeeding
INR > 2-3.0
Severe renal impairment (CrCl < 15ml/min)
DOACs interactions
Active malignancy/chemotherapy
What is the target INR and range for acute MI (high risk)? (2)
Target = 2.5
Range 2-3
What is the target INR and range for AF? (2)
Target = 2.5
Range = 2-3
What is the target INR and range for mechanical valve + risk factors? (2)
Target = 3
Range = 2.5-3.5
What is the target INR and range for mechanical valve with systemic embolism despite adequate anticoagulation? (2)
Target (3)
Range (2.5-3.5)
What is the target INR and range for VTE? (2)
Target (2.5)
Range (2-3)
What do you need to consider when starting patients on warfarin? (4)
Calculate TTR per visit:
- Exclude measurements taken during first 6 weeks of tx.
- Calculate TTR over a maintenance period of at least 6 months.
Reassess a person with poor anticoagulant control shown by any of the following:
- 2 INR values > 5 or 1 INR value > 8 within the past 6 months.
- 2 INR values < 1.5 within past 6 months.
- TTR < 65%
Identify patient factors:
- Cognitive function
- Adherence to medicine
- Illness
- Interactions
- Lifestyle factors (diet and alcohol)
Alt therapy if poor anticoagulation control can’t be improved.
What is the dosing schedule if rapid anticoagulant is required? (2)
Give 5mg OD for 2 days and re-measure person’s INR on day 3.
Subsequent doses depend on prothrombin time reported as INR.
What is the dosing schedule where an immediate effect is required? (2)
Heparin or LMWH is given concomittantly (secondary care only)
48-72 hrs for anticoagulant effect of warfarin to fully develop.
What is the dosing schedule for people with AF? (2)
No need to achieve anticoagulation rapidly, a slow loading regimen is sage and achieves therapeutic anticoagulation in majority of people within 3-4 weeks.
Warfarin 1-2mg daily = acceptable starting dose. Average daily maintenance dose = 5mg daily.
What is the INR monitoring requirements for initiating therapy? (4)
Check INR within 2-3 days (out px)
Daily INR/PT in hospital until therapeutic x2 days.
Check 1 week after initiation steady state.
Monitor weekly during first month of therapy.
What are the INR monitoring requirements for maintenance therapy? (3)
If you have to hold a dose, recheck within 1-2 days.
If you change a dose, recheck within 1-2 weeks.
Routine follow up for stable, reliable patients is every 4 weeks (may consider 6 weeks in some px), more often (every 1-2 weeks) in less reliable.unstable px.
State the tx duration for distal DVT with temporary risk factor = surgery. (1)
At least 6 weeks.
State the tx duration for distal DVT with temporary risk factor other than surgery (1)
At least 3 months.
State the tx duration for proximal DVT/PE with temporary risk factor. (1)
At least 3 months.
State the tx duration for any presentation with continuing risk factors. (1)
At least 6 months.
State the tx duration for idiopathic DVT or PE, idiopathic no risk factors will be identified but the person is assumed to have a continuing risk of VTE. (1)
At least 6 months.
State the tx duration for AF. (1)
Lifelong
Give e.g of drugs that increases INR. (16)
Thyroid products
Metronidazole
Fluconazole/azole
2nd, 3rd generation cephs
B-road spectrum ABx
Alcohol
Amiodarone
Azithromycin
Statins
Omeprazole
Phenytoin
Bactrim
Heparin
Gemfibrozil
Fluoroquinolones
Cimetidine
Give e.g of drugs that reduce INR. (9)
Estrogen
Vitamin K
Alcohol
Carbamazepine
Barbiturates
Phenytoin
Rifabutin
Rifampicin
Ritonavir
Give e.g of drugs that has no INR effect. (5)
Aspirin
Clopidogrel
COX2 inhibitors
Glycoprotein IIb/IIIa antagonists (Tirofiban)
NSAIDs
What are the common foods/natural products interactions to Warfarin? (17)
Glucosamine
Ginseng
Fish Oil
Ginkgo biloba
St. John’s Wort
Chondroiton
Vitamin E
Seaweed
Garlic
Ginger
Saw Palmetto
Green leafy vegetables
Soya
Mayonnaise
Ice Cream
Cranberry
Green Tea
What are the common s/e of warfarin? (4)
Haemorrhage
Major (life threatening/occurs in critical organ. Stop bleed > thrombotic risk)
Minor (Epistaxis, Macroscopic Haematuria, Muscle Hematoma, ID source bleeds
Calciphylaxis / Skin necrosis.
Explain how you would deal with major bleeds. (4)
Stop warfarin, give Phytomenadione
5-10mg slow I.V. Inj
Prothrombin complex (factors II, VII, IX, X)
Fresh frozen plasma
Explain how you would deal with INR > 8. (4)
No bleeding/minor bleeding = stop warfarin.
Restart = INR < 5
If other risk factors for bleeding, give vitamin K 500mcg slow I.V. Injection / 5mg Po.
Repeat Vitamin K dose if INR still too high after 24 hrs.
