Stroke Flashcards
What is stroke?
Sudden onset of focal neurologic deficit resulting from the interruption of blood flow to an area in the brain (similar to ischemia in heart attacks)
What are some consequences of stroke?
Deficits depend on area of brain affected:
Hemiplegia (monolateral paralysis)
Hemiparesthesia (monolateral numbness)
Blindness in one eye
Speech disturbance
More general symptoms (dizziness, weakness, headaches, confusion)
What is FAST in terms of stoke?
It descibes four common symptoms of a stroke
F(ace is it drooping?)
A(rms can you raise both?)
S(peech is it slurred or jumbled?)
T(ime to call 911 right away)
What is the most devastating thing about stroke?
The disability that can develop due to brain damage.
Is stroke risk the highest in younger patients?
No, it tends to increase greatly following retirement age (over 65), but begins to climb at 50
Why should we agressive in reducing stroke risk?
We can prevent unnecessary severe disability following a preventable stroke
What is a transient ischemic attack (TIA)?
They are a focal neurological deficit as a result of ischemia lasting less than 24 hours and without evidence of infarction on imaging studies (no equivalent for troponin)
What is the risk of a full-blown stroke in patients that have had a transient ischemic attack (TIA)?
7.5-17.4% risk of stroke within 3 months, and 50% of these strokes occur within 48 hours
Due to such a high risk, these patients should be considered for secondary prevention
What are the main types of stroke?
Ischemic (87% of cases)
Hemorrhagic (13%)
Describe hemorrhagic strokes?
They have…
Higher death rate
HIgher morbidity
Risk factors: aneurysm, hypertension, and DAPT
What are the four types of ischemic stroke?
The main two types are:
Atherosclerotic (20%)
Cardioembolic (20%)
The other two are the following:
Cryptogenic (30%) unknown cause
Lacunar (25%) small vessel stroke
Other causes (5%)
What causes the damage in hemorrhagic stroke?
Ischemia from hemorrhaging can starve brain tissue form oxygen.
The BBB protects neurons from blood, so in hemorrhagic stroke the neurons are exposed to blood. This causes inflammatory response
What can cause cardioembolic stroke
?
Thrombi (clots) can break off and travel through the aorta —> carotid arteries —> small cerebral vessels
The thrombi fragments get stuck in the small cerebral vessels, the obstruction causes ischemia
What conditions pose a greater risk for thrombus generation within or on the heart?
Atrial fibrillation (intra-atrial thrombus)
Mechanical heart valves (valvular thrombus)
How is cardioembolic stroke preventing?
Prevention is often focuses on the use of anticoagulant medications (warfarin, DOACs)
How is a cardioembolic stroke diagnosed?
If a patient has a stroke, it is determined to be cardioembolic by the following results:
ECG findings of atrial fibrillation (increased risk for atrial clots)
Left atrial thrombus
Absence of significant atherosclerosis on imaging/ultrasound
What should patients do if a patient experiences signs of stroke?
Send them to the emergency, it is important to get an objective diagnosis required for accuracy
Advanced imaging is used to determine:
Ischemia vs. Hemorrhage
Alternate diagnosis (tumour)
What is done in the hospital when a patient presents a stroke?
Everyone eligible for a fibrinolytic is given one, it is the only repurfusion strategy. Needs to be given within 3h of onset of symptoms to be effective
Can be given between 3-4.5h in patients under 80, DOAC use, severe stroke, history of stroke and diabetes
What are fibrinolytics?
They are plasminogen activators (conversion of plasminogen into plasminogen). Plasminogen breaks down fibrin clots
What are the two commonly used fibrinolytic in Canada?
Alteplase (tPA): Requires 1h infusion time
Tenecteplase (Can be administered with a single IV bolus dose)
What will happen if fibrinolytics are given after 3-4.5h after onset of stroke symptoms?
No efficacy, and providing tPA at this stage increases bleeding risk unnecessarily (without any benefit)
Hemorrhagic bleeding does not occur in ischemic stroke, True or False?
False, in higher severity ischemic stroke, the risk of intracerebral hemorrhage, but the use of plasminogen activators (fibrinolytics) is still a net benefit (prevent disability)
What are the indications or tPA use?
Clearly defined onset within the past 3h
Significant neurologic deficit (is it worth the risk of intracerebral hemorrhagic bleeding)
What are some contraindications with tPA use?
Rapidly improving condition
Hemorrhage on CT (we need clotting instead)
Seizure at stroke onset
Recent stroke or head trauma (3months)
Recent GI/UTI bleed
High BP (185/110)
Low platelets
Recent anticoagulant use (within 2 days)
History of ICH
Are anticoagulants used with tPA in stroke?
No, the addition of an anticoagulants does not significantly change patient outcomes. Therefore there is no reason to give the patient an anticoagulants
What should be done in stroke patients who are ineligible for tPA?
Antiplatelet therapy is initiated (most often Aspirin)
What are some antiplatelet agents used in stroke?
COX inhibitors (Aspirin) first choice in most cases
ADP receptor antagonists (Clopidrogrel, Prasugrel, Ticagrelor)
Interference with cyclic AMP (Dipridamole/ASA)
How is Aspirin (COX inhibitor) cardio protective?
Low dose ASA (81mg), it selectively inhibits COX-1 enzyme. This enzyme is responsible for producing Thromboxane A2, a major clotting (amplifies platelet and clotting activity)
Are NSAIDs other than Aspirin indicated in stroke?
NO, they are not COX-1 selective at any dose
What is the benefit of taking ASA in secondary prevention stroke?
Reduce risk for subsequent stroke by 16%
Recommended dose (50-100mg/day)
In what type of stroke patients is ASA not used?
Certain patients with AFIB/cardioembolic risks
Hemorrhagic stroke
Other contraindications
Can ASA cause major bleeding?
Yes, 0.4% chance per year
Incidence increases with:
Dose
Hemostatic defect
Previous GI bleeds
Drugs
Age over 60
Uncontrolled HTN
CKD
Does clopidrogrel have a safer side effect profile vs. ASA?
No, they are almost the same. ASA is significantly cheaper though
What are the guidelines for antiplatelet use following non-cardioembolic stroke (secondary prevention)?
First line:
ASA (50-325mg OD)
Aggrenox BID (ASA 25mg + dipyridamole 200mg)
Second line:
Clopidrogrel 75mg OD
DAPT has a slim criteria for use in minor stroke. ASA + Clopidrogel is used for the first 21 days followed by ASA alone in patients with minor stroke
What is dipyridamole?
It is not used very often
Administered BID (200mg/25mg)
It is a PDE inhibor/adenosine inhibitor/promoter of prostaglandins (PGI2)
Possibly better than ASA alone for secondary prevention of stroke
Is Ticagrelor better at reducing risk following a stroke (secondary prevention)?
Ticagrelor is slightly better, but basically the same at reducing risk. But Ticagrelor is more expensive vs. Aspirin. Ticagrelor will eventually be a second line option like Clopidogrel
What is the role of DAPT after stroke?
It is limited, but important
Used in:
Non-disabling stroke (without the classic signs of stroke)
HIgh Risk TIA (transient ischemic attack)
tPA was not administered to these patient, because their condition was not severe enough
Review table on page 62 for a complete diagram of drug choices in stroke
What is deep vein thrombosis (DVT)?
A clot forms in one of the big veins in your legs.
This obstruction can cause swelling
Pieces of these clots can break off and enter the veins in the lungs. This can cause a pulmonary embolism
How can the risk for clotting in peripheral veins reduced?
Support mobility
Low dose heparin
LMWH
What drugs do patients receive for secondary prevention of stroke?
Anti-platelet therapy:
(cardioembolic stroke patients get ASA, non-cardioembolic P stroke patients get oral anticoagulants ex. Warfarin and DOACs)
Blood pressure reduction:
(ACE+TZD, goal=140/90)
Cholesterol reduction:
Statins are indicated in all patients with clinical atherosclerosis (99% of stroke patients are indicated for statins)
Lifestyle changes:
(Improve diet, activity, smoking cessation, physiotherapy)
Is blood pressure following a heart attack high?
Yes, but it is not to be reduced in the first 72 hours following onset of symptoms.
It is only lowered if the following conditions are met:
BP higher than 220/120
OR
If they are using thrombolysis and BP is 185/110
Should patients who have experienced be given a BP reducing drug blindly?
Strong consideration for treating everyone post-stroke regardless of BP (target =140/90)
Use ACE+TZD
Does ACEi alone as a BP reduction therapy following a stroke effective?
No, it has similar effects as placebo when used alone
Need to use combo therapy (ACEi+TZD)
Does ASA have better risk reduction in patients who had a non-cardioembolic stroke vs. Warfarin?
ASA 325 (antiplatelet) vs. Warfarin (anticoagulant)
Warfarin did not reduce events significantly vs. ASA
Warfarin also has a higher bleeding risk, so ASA is used instead
Are anticoagulants preferred in non-cardioembolic stroke therapy?
No, antiplatelet (ASA) is preferred over anticoagulants for atherosclerotic stroke management
Warfarin (anticoagulant) is not recommended unless the stroke is cardioembolic
What score is used to determine the necessity of drug therapy for stroke risk reduction in patients with atrial fibrilation?
The CHADS-65
Heart failure (C)HF
(H)ypertension
(A)ge
(D)iabetes
(S)troke (prior)
Is ASA used routinely in primary prevention of strokes?
No, if you do not have any of the risk factors/diseases, do not use ASA. Benefit of ASA in primary prevention is too low for the risks of using ASA (major bleeding risk)
