Prevention of Stroke
DAVID DOIG & NICK WARD
UCL INSTITUTE OF NEUROLOGY
QUEEN SQUARE
n.ward@ucl.ac.uk
For more information go to
http://www.ucl.ac.uk/ion/departments/sobell/Research/NWard
Objectives
• Review the common mechanisms for ischaemic stroke
• Give examples of how to investigate ischaemic stroke
• Outline the medical options for stroke prevention
• Know the surgical options for stroke prevention
• Know some advantages and disadvantages of each treatment
Pathogenesis of Ischaemic Stroke
• Embolism
– Carotid or vertebral artery disease (atheroma, dissection)
– Cardiac disease (arrhythmia, thrombus, PFO)
• Arterial occlusion (in-situ atheroma)
– Caused by exposure to risk factors over time
– Coagulation disorder
• Rare causes
Primary Prevention
Primary Prevention
• Lifestyle risk factor modification
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High blood pressure
High cholesterol
Smoking
Alcohol intake
Physical activity
Obesity
• Most interventions work through multiple mechanisms
Secondary Prevention
Medical Therapy
Antiplatelet Drugs
• Aspirin inhibits COX and thromboxane A2
• Dipyridamole inhibits platelet phosphodiesterase
• Clopidogrel blocks platelet ADP receptors
• There is an increase in bleeding risk with antiplatelets
Antihypertensive Drugs
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The higher the blood pressure, the higher the risk
Recommended target of 130/80mmHg or lower
There is no definitive evidence that one agent is better
The elderly experience more side-effects
Up to date guidelines http://www.bhsoc.org/latest-guidelines/
Anticholesterol Drugs
• Statins reduce LDL and total cholesterol
• They are HMG-CoA reductase inhibitors
• They may stabilize plaque / improve endothelial fn
Anticoagulants
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Warfarin prevents fibrin clots rather than platelet clots
Previous stroke is a major risk factor for recurrent stroke in AF
Monitored to target INR 2.0 to 2.5
Major bleeding risk of around 1.3% per annum
Much bigger reduction in stroke than just aspirin
Balance risk reduction with bleeding risk with CHADS-2 score
0 = aspirin, 1= either, 2+ = warfarin
Diabetes
• Good glycaemic control prevents microvascular complications
• Good glycaemic control might prevent macrovascular
complications
• Intensive treatment of BP / cholesterol reduces risk
Secondary Prevention
Surgical Options
Patent Foramen Ovale
• Population incidence 10-20%?
• To cause stroke
– Must be of sufficient size
– Right-to-left shunt
• Investigations
– TTE
– TOE
– Bubble study
No better than „medical therapy? Furlan et al., NEJM 2012; 366:991-999
Carotid Artery Disease
• Thrombosis on unstable plaque and embolism
• Responsible for about 10% of stroke
Investigating Carotid Artery Disease
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Ultrasound (carotid artery doppler ultrasound)
CT angiogram
MR angiogram
Catheter angiogram
• The percentage stenosis guides intervention
Carotid Doppler Ultrasound
• Non-invasive
• Inexpensive
• Measures velocity of blood
– Converted to % stenosis
CT and MR angiogram
• Heart to head
• IV contrast
– Avoid in renal failure
– Risk of allergic reaction
• % stenosis measured
Catheter Angiogram
• The “gold standard”
• Risk of stroke around 1%
Severe ICA stenosis
Common carotid artery
When to Revascularize
• Severe symptomatic carotid stenosis (70 – 99%)
• Moderate symptomatic carotid stenosis (50 – 69%)
• Less than 50% not suitable for intervention
– Risk of recurrent stroke outweighed by procedural risk
• Intervene in asymptomatic patients?
Carotid Endarterectomy
Carotid Stenting – an alternative
Complications of stenting
• Stroke or death
– Around 7% risk
• Cardiac complications
– Bradycardia / asystole
– Myocardial infarction
• Groin haematoma
– Transfusion
– Re-operation
• “Silent” brain lesions
– Effect on cognition
Choice of Carotid Procedure
• At the moment surgery is the treatment of choice
• Higher procedural risk of stroke and myocardial infarction
with stenting in the elderly
• But there is less cranial nerve injury / haematoma
• And a general anaesthetic may be avoided
Summary of Secondary Prevention of Stroke
Strategy
Relative risk reduction
NNT at 1 year
BP reduction
28%
51
Cholesterol reduction
25%
57
Warfarin for AF
62%
13
Stopping smoking
33%
43
Aspirin
28%
77
Carotid endarterectomy
(mod / severe stenosis)
44%
26
JAMA 288(11):1388-1395