D. Warfarin – Explanation

The patient has been diagnosed with atrial fibrillation. The symptoms of stroke were probably due to
atrial fibrillation.

The main goals in managing AF are rate/rhythm control and anticoagulation. As she was already
managed with metoprolol which is a rate limiting medication, the next step is to count her CHA2DS2-VASc
score to determine if she requires anticoagulation. In her case, she would have a CHA2DS2-VASc score
of 4 (1 for hypertension, 1 for age, 1 for stroke history and 1 for sex). Anticoagulation such as warfarin
would be of benefit to reduce the risk of stroke for her.

Aspirin is no longer used for stroke prevention.

ATRIAL FIBRILLATION AND ANTICOAGULATION, CHA2DS2-VASc
NICE suggest using the CHA2DS2-VASc score to determine the most appropriate anticoagulation strategy
for atrial fibrillation. The CHA2DS2-VASc score is used to assess a patient’s stroke risk. Offer
anticoagulation to all people with a CHA2DS2-VASc of 2 or above, and consider offering it to men with a
CHA2DS2-VASc of 1.

In practice, the HAS-BLED score is also usually calculated to identify patients at high risk of bleeding who
could benefit from increased vigilance and a specific focus on correction of modifiable risk factors. The
decision to start treatment with an anticoagulant should invole consideration of a balance between the
benefits in stroke reduction, the adverse effects of increasing bleeding risk, and particularly risk of
haemorrhagic stroke.

For the purpose of the exam (and only for the exam), we have tried to simplify this. It may be quicker to
remember when to give warfarin according to the below scenarios instead of writing out and calculating
the whole CHA2DS2-VASc score. This only applies to simple exam scenarios.
 < 65 years old and no comorbidies → No warfarin
 ≥ 65 years old or at least one comorbidity → warfarin
Another alternative to warfarin which has gained much popularity over the past decade are DOAC (DirectActing Oral Anticoagulants) such as apixaban, edoxaban and rivaroxaban. These medications are also
licensed for use for stroke prevention with non-valvular atrial fibrillation and a CHA2DS2-VASc score ≥ 2
(consider for men with CHA2DS2-VASc score ≥ 1).

The benefits of using DOAC compared to warfarin include:
 Reduces the risk of intracranial haemorrhage
 No INR monitoring
 Faster onset anticoagulation (2-4 hours)
The disadvantages of using DOAC compared to warfarin include:
 No specific antidote
 Essential to be compliant
Newer questions for the exam may contain DOAC as an option so do read up on them.

SECONDARY PREVENTION AFTER STROKE OR TIA
Stroke: A syndrome of the sudden onset of focal neurological loss of presumed vascular origin lasting
more than 24 hours

Transient Ischaemic Attack: A syndrome of the sudden onset of focal neurological loss of presumed
vascular origin lasting less than 24 hours.

The following are important notes to remember as part of secondary prevention in stroke or TIA
once it is confirmed:

• Lower BPo Aim for target Blood Pressure of 130/80
  Note: Do not start controlling BP in first 48 hours as this may cause extension of stroke
  o Age ≥ 55 or black patient of any age start a calcium channel blocker
  o Age > 55 start ACE inhibitor or Angiotensin-(II) receptor antagonists if ACE inhibitor not
  tolerated
  o Add ACE inhibitor, calcium channel antagonist, or thiazide diuretc if target not achieved with
  initial choice
  Note: BP management for secondary prevention in stroke and TIA is unlikely to be
  asked during the exam as SIGN and NICE guidelines differ slightly. SIGN recommends
  using thiazides and ACE inhibitors in all, even if normotensive.
• Lower Cholesterolo Aim for 40% reduction in non-HDL cholesterol
  o Statins to be taken daily lifelong after TIA or ischaemic stroke
   Note: Statins for all regardless of baseline cholesterol
   80 mg atorvastatin recommended by both NICE and SIGN
• Use antiplatelet or anticoagulation treatment in ischaemic stroke/TIA
  o This largely depends if atrial fibrillation is present
  o Atrial fibrillation present:
   Use an anticoagulation: Warfarin, Dabigatran, Rivaroxaban, Apixaban, Edoxaban
  (Warfarin target INR range 2.0-3.0
   Note: In the acute setting:
  o If TIA and imaging has excluded haemorrhage, start anticoagulation
  immediately
  o If disabling ischaemic stroke, defer anticoagulation treatment for 14 days from
  onset. In the interim, aspirin 300 mg daily can be used.
  o Atrial fibrillation absent:
   Give clopidogrel 75 mg OD for long-term prevention of ischaemic events
   If intolerant of clopidogrel, give aspirin 75 mg OD plus dipyridamole MR 200 mg BD
  o And again if this is not tolerated use either aspirin or dipyridamole alone
   Note: For acute treatment of ischaemic stroke give 300 mg of Aspirin for 2 weeks
• Lifestyle adviceo Low salt diet
  o Low cholesterol diet
  o Weight loss
  o Alcohol reduction
  o Smoking cessation

Lastly, always consider carotid endarterectomy as secondary prevention in ischaemic stroke

 Carotid duplex is done as part of workup at TIA clinic to consider carotid endarterectomy if
internal carotid artery is stenosed (stenosis is ≥ 50% in men, ≥ in women)
o Guidelines recommend this should eb done within 2 weeks of admission (SIGN & NICE)

Special key notes from SIGN Guidelines regarding secondary prevention after haemorrhagic
strokes:

 BP control is important
 Do not offer antiplatelets, unless at high risk of a cardiac event
 Statins are not recommended