Haematology - SPAF Flashcards
Describe the pathophysiology of Stroke in AF.
Irregular contraction of the left ventricle creates turbulent flow that results in the accumulation of clotting factors in the left atrial appendage. This may precipitate thrombus formation. The thrombus may embolise to the cerebral circulation manifesting in stroke.
What is the first thing to determine w AF?
If pt has mod-severe mitral stenosis or mechanical valves.
If yes, DOACs CI –> use VKA (warfarin)
What are the goals of SPAF?
- Re-est vascularisation to brain
- Avoid risk of haemorrhagic conversion (manage BP)
- Prevent systemic embolism
- Balance anticoagulation and avoiding major bleeding
How do we determine whether to anticoagulate?
CHA2DS2-VASc criteria
0: No need to anticoagulate.
1: Watch and wait till another risk factor develops. May consider anticoagulation.
2: Start anticoagulation.
What is the CHA2DS2-VASc criteria?
C: CHF
H: HTN
A2: Age >=75y.o.
D: DM
S2: Hx of stroke
V: Vascular disease
A: Age >=65y.o.
Sc: Gender (F) - often left off
What is the point of HASBLED criteria?
It helps to profile bleeding risk so we can mitigate modifiable risk factors. It is validated for AF pts.
What is the HASBLED criteria?
H: Uncontrolled HTN (SBP>160 mm Hg)
A:
- Abnormal renal fn: HD/PD, renal transplant, SCr >200 micromol/L
- Abnormal LFT: cirrhosis, ASP, AST, ALP >3ULN, bilirubin>2ULN
S: Hx of stroke
B: Bleeding predisposition, Hx
L: Labile INR
E: Elderly (age >65y.o.) or extreme frailty
D: Drugs (antithrombotics, NSAIDs) and alc (M>14units, F>7units)
What are the anticoagulation options in SPAF?
Dabigatran, Rivaroxaban, Apixaban, Edoxaban, Warfarin
Are antiplatelets used in SPAF?
NO. “ILLEGAL”
Describe the renal dosing adjustments for the DOACs.
Dabigatran:
- Adjustments start from <30mL/min: CI , [FDA]15-30mL/min: 75mg BD
Rivaroxaban:
- Adjustment starts from 30-50mL/min, [FDA] 15-49 mL/min: 15mg per day, 15-30mL/min: Use w caution, <15mL/min: CI
Apixaban:
- 5mg BD (normal)
- CrCL> 30mL/min look at criteria - Min 2 criteria: Age >=80y.o., Body wt <60kg, SCr >1.5mg/dL or 133micromol/L –> 2.5mg BD
- Adjustment starts from <30mL/min: 2.5 mg BD, <15mL/min
- HD pts not well studied, not incl in clinical trials
Edoxaban:
- 60 mg per day (normal)
- If any of the following - CrCL 30-50mL/min, wt <=60kgm, concomitant verapamil, quinidine, dronedarone –> 30 mg per day
- CrCL <15-30mL/min: 30mg per day, CrCL<15 mL/min: Not reco
For estimating renal dose adjustments in SPAF what considerations are there?
Use Cockcroft-Gault eqn
What special dosing remarks are there for the DOACs?
Dabigatran & rivaroxaban dosing is NOT based on criteria (js CrCL) while apixaban and edoxaban are criteria based (Scr, wt, age)
What to do if pt has high bleeding risk HASBLED >=3?
- Assess risk of stroke bleeding
- ID & treat other comorbidities
- ID cause of prev bleeding
If unknown, untreatable, irreversible: no treatment, LAA occlusion (filter to catch embolus)
If known & treatable: restart OAC (DOAC >VKA)
What are the principles of anticoagulation selection?
VKA decreases risk of stroke by 64% & death by 26% in pts w AF.
DOACs further decrease risk of AIS by 19% and risk of ICH by 50% vs VKA (warfarin)
When are DOACs preferred over VKA for SPAF?
Always, except in mod-severe mitral stenosis, prosthetic heart valves, antiphospholipid syndrome.
